Revert "Actually use the 'user_filter' configuration option"
Revert "Actually use the 'user_filter' configuration option"

This reverts commit e9d4587ff11c8510f01dfa184414f73d75b4550b, which is
incompatible with GitLab's built in LDAP user filter: a GitLab LDAP
filter is [added on top of the other filters used to find the
user](https://gitlab.com/gitlab-org/gitlab-ce/blob/982d4d51e8110bec280eb00db0fb756b062103d9/lib/gitlab/ldap/adapter.rb#L61)

Example GitLab LDAP filter: `(memberOf=cn=foo,dc=bar)`.

In contrast, an omniauth-ldap filter [replaces the 'normal'
filters](https://gitlab.com/gitlab-org/omniauth-ldap/blob/76d77543dec0c585bb4e974262f43675f9810953/lib/omniauth/strategies/ldap.rb#L55)

Example omniauth-ldap user filter:
`(&(uid=%{username})(memberOf=cn=foo,dc=bar))`.

fgbreel/gitlabhq,per-garden/gitlabhq,Exeia/gitlabhq,gopeter/gitlabhq,fpgentil/gitlabhq,NKMR6194/gitlabhq,michaKFromParis/gitlabhqold,mmkassem/gitlabhq,Exeia/gitlabhq,louahola/gitlabhq,fearenales/gitlabhq,NARKOZ/gitlabhq,jvanbaarsen/gitlabhq,bigsurge/gitlabhq,bozaro/gitlabhq,tim-hoff/gitlabhq,dreampet/gitlab,mrb/gitlabhq,koreamic/gitlabhq,sue445/gitlabhq,szechyjs/gitlabhq,revaret/gitlabhq,yatish27/gitlabhq,gorgee/gitlabhq,theodi/gitlabhq,dvrylc/gitlabhq,DanielZhangQingLong/gitlabhq,initiummedia/gitlabhq,michaKFromParis/sparkslab,flashbuckets/gitlabhq,TheWatcher/gitlabhq,Datacom/gitlabhq,dplarson/gitlabhq,initiummedia/gitlabhq,shinexiao/gitlabhq,gorgee/gitlabhq,liyakun/gitlabhq,yama07/gitlabhq,Devin001/gitlabhq,yama07/gitlabhq,screenpages/gitlabhq,pulkit21/gitlabhq,Exeia/gitlabhq,WSDC-NITWarangal/gitlabhq,zrbsprite/gitlabhq,NKMR6194/gitlabhq,nmav/gitlabhq,chadyred/gitlabhq,Keystion/gitlabhq,gopeter/gitlabhq,Telekom-PD/gitlabhq,OtkurBiz/gitlabhq,youprofit/gitlabhq,ikappas/gitlabhq,darkrasid/gitlabhq,initiummedia/gitlabhq,zrbsprite/gitlabhq,michaKFromParis/sparkslab,johnmyqin/gitlabhq,Kambda/mobbr-gitlabhq,jrjang/gitlab-ce,allysonbarros/gitlabhq,delkyd/gitlabhq,axilleas/gitlabhq,ngpestelos/gitlabhq,yfaizal/gitlabhq,SVArago/gitlabhq,vjustov/gitlabhq,LytayTOUCH/gitlabhq,cui-liqiang/gitlab-ce,sonalkr132/gitlabhq,Telekom-PD/gitlabhq,ferdinandrosario/gitlabhq,OlegGirko/gitlab-ce,bigsurge/gitlabhq,louahola/gitlabhq,fearenales/gitlabhq,Razer6/gitlabhq,openwide-java/gitlabhq,dvrylc/gitlabhq,LytayTOUCH/gitlabhq,wangcan2014/gitlabhq,szechyjs/gitlabhq,gorgee/gitlabhq,hacsoc/gitlabhq,DanielZhangQingLong/gitlabhq,Kambda/mobbr-gitlabhq,SkyWei/gitlabhq,akumetsuv/gitlab,ttasanen/gitlabhq,DanielZhangQingLong/gitlabhq,OtkurBiz/gitlabhq,t-zuehlsdorff/gitlabhq,sakishum/gitlabhq,mr-dxdy/gitlabhq,SkyWei/gitlabhq,phinfonet/mobbr-gitlabhq,dwrensha/gitlabhq,bigsurge/gitlabhq,eliasp/gitlabhq,sonalkr132/gitlabhq,ikappas/gitlabhq,hacsoc/gitlabhq,julianengel/gitlabhq,SVArago/gitlabhq,bozaro/gitlabhq,OlegGirko/gitlab-ce,icedwater/gitlabhq,tim-hoff/gitlabhq,martijnvermaat/gitlabhq,Kambda/mobbr-gitlabhq,fendoudeqingchunhh/gitlabhq,michaKFromParis/gitlabhqold,delkyd/gitlabhq,gopeter/gitlabhq,sideci-sample/sideci-sample-gitlabhq,bbodenmiller/gitlabhq,wangcan2014/gitlabhq,kemenaran/gitlabhq,folpindo/gitlabhq,sue445/gitlabhq,tk23/gitlabhq,ayufan/gitlabhq,allysonbarros/gitlabhq,nmav/gitlabhq,hq804116393/gitlabhq,LytayTOUCH/gitlabhq,NuLL3rr0r/gitlabhq,fpgentil/gitlabhq,michaKFromParis/gitlabhq,initiummedia/gitlabhq,mente/gitlabhq,allysonbarros/gitlabhq,phinfonet/mobbr-gitlabhq,cncodog/gitlab,salipro4ever/gitlabhq,fpgentil/gitlabhq,ksoichiro/gitlabhq,wangcan2014/gitlabhq,pjknkda/gitlabhq,Datacom/gitlabhq,youprofit/gitlabhq,LUMC/gitlabhq,iiet/iiet-git,yfaizal/gitlabhq,pkgr/gitlabhq,whluwit/gitlabhq,zBMNForks/gitlabhq,sue445/gitlabhq,liyakun/gitlabhq,rebecamendez/gitlabhq,kitech/gitlabhq,fantasywind/gitlabhq,H3Chief/gitlabhq,jvanbaarsen/gitlabhq,johnmyqin/gitlabhq,childbamboo/gitlabhq,ksoichiro/gitlabhq,stellamiranda/mobbr-gitlabhq,Razer6/gitlabhq,8thcolor/testing-public-gitlabhq,fscherwi/gitlabhq,cncodog/gitlab,bbodenmiller/gitlabhq,liyakun/gitlabhq,axilleas/gitlabhq,jrjang/gitlabhq,larryli/gitlabhq,sekcheong/gitlabhq,fantasywind/gitlabhq,nguyen-tien-mulodo/gitlabhq,jvanbaarsen/gitlabhq,childbamboo/gitlabhq,Keystion/gitlabhq,manfer/gitlabhq,mmkassem/gitlabhq,since2014/gitlabhq,stanhu/gitlabhq,WSDC-NITWarangal/gitlabhq,ttasanen/gitlabhq,bladealslayer/gitlabhq,akumetsuv/gitlab,ayufan/gitlabhq,123Haynes/gitlabhq,mente/gitlabhq,jrjang/gitlab-ce,yama07/gitlabhq,mathstuf/gitlabhq,it33/gitlabhq,dukex/gitlabhq,t-zuehlsdorff/gitlabhq,Devin001/gitlabhq,tempbottle/gitlabhq,williamherry/gitlabhq,chenrui2014/gitlabhq,yonglehou/gitlabhq,rumpelsepp/gitlabhq,Burick/gitlabhq,8thcolor/testing-public-gitlabhq,revaret/gitlabhq,jirutka/gitlabhq,zrbsprite/gitlabhq,folpindo/gitlabhq,copystudy/gitlabhq,tim-hoff/gitlabhq,lvfeng1130/gitlabhq,koreamic/gitlabhq,hq804116393/gitlabhq,Burick/gitlabhq,Kambda/Mobbr,akumetsuv/gitlab,flashbuckets/gitlabhq,chenrui2014/gitlabhq,fantasywind/gitlabhq,adaiguoguo/gitlab_globalserarch,SVArago/gitlabhq,MauriceMohlek/gitlabhq,youprofit/gitlabhq,yama07/gitlabhq,k4zzk/gitlabhq,salipro4ever/gitlabhq,NKMR6194/gitlabhq,rfeese/gitlab-ce,julianengel/gitlabhq,hzy001/gitlabhq,mavimo/gitlabhq,xuvw/gitlabhq,NARKOZ/gitlabhq,MauriceMohlek/gitlabhq,Datacom/gitlabhq,daiyu/gitlab-zh,salipro4ever/gitlabhq,yulchitaj/TEST3,ngpestelos/gitlabhq,shinexiao/gitlabhq,jirutka/gitlabhq,yuyue2013/ss,Telekom-PD/gitlabhq,sakishum/gitlabhq,stanhu/gitlabhq,sekcheong/gitlabhq,allistera/gitlabhq,vjustov/gitlabhq,per-garden/gitlabhq,SkyWei/gitlabhq,chadyred/gitlabhq,rebecamendez/gitlabhq,rfeese/gitlab-ce,shinexiao/gitlabhq,t-zuehlsdorff/gitlabhq,fearenales/gitlabhq,Keystion/gitlabhq,yonglehou/gitlabhq,TheWatcher/gitlabhq,aaronsnyder/gitlabhq,fgbreel/gitlabhq,sue445/gitlabhq,pjknkda/gitlabhq,ferdinandrosario/gitlabhq,H3Chief/gitlabhq,darkrasid/gitlabhq,sekcheong/gitlabhq,daiyu/g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amic/gitlabhq,Devin001/gitlabhq,lvfeng1130/gitlabhq,since2014/gitlabhq,since2014/gitlabhq,yatish27/gitlabhq,ksoichiro/gitlabhq,atomaka/gitlabhq,htve/GitlabForChinese,OlegGirko/gitlab-ce,allistera/gitlabhq,Telekom-PD/gitlabhq,yatish27/gitlabhq,cinderblock/gitlabhq,pkgr/gitlabhq,dukex/gitlabhq,dreampet/gitlab,jrjang/gitlabhq,stoplightio/gitlabhq,ttasanen/gitlabhq,mrb/gitlabhq,mrb/gitlabhq,windymid/test2,iiet/iiet-git,pulkit21/gitlabhq,theodi/gitlabhq,kemenaran/gitlabhq,ikappas/gitlabhq,ngpestelos/gitlabhq,cui-liqiang/gitlab-ce,ZeoAlliance/gitlabhq,aaronsnyder/gitlabhq,revaret/gitlabhq,theonlydoo/gitlabhq,Burick/gitlabhq,dwrensha/gitlabhq,flashbuckets/gitlabhq,jaepyoung/gitlabhq,sonalkr132/gitlabhq,szechyjs/gitlabhq,kemenaran/gitlabhq,Tyrael/gitlabhq,hzy001/gitlabhq,revaret/gitlabhq,allistera/gitlabhq,ibiart/gitlabhq,OlegGirko/gitlab-ce,yulchitaj/TEST3,mavimo/gitlabhq,htve/GitlabForChinese,rumpelsepp/gitlabhq,axilleas/gitlabhq,copystudy/gitlabhq,duduribeiro/gitlabhq,dwrensha/gitlabhq,zBMNForks/gitlabhq,manfer/gitlabhq,yfaizal/gitlabhq,fscherwi/gitlabhq,lvfeng1130/gitlabhq,atomaka/gitlabhq,stanhu/gitlabhq,szechyjs/gitlabhq,williamherry/gitlabhq,tempbottle/gitlabhq,yatish27/gitlabhq,chenrui2014/gitlabhq,mathstuf/gitlabhq,michaKFromParis/gitlabhq,mmkassem/gitlabhq,NuLL3rr0r/gitlabhq,SkyWei/gitlabhq,stellamiranda/mobbr-gitlabhq,123Haynes/gitlabhq,fantasywind/gitlabhq,joalmeid/gitlabhq,nmav/gitlabhq,nguyen-tien-mulodo/gitlabhq,tk23/gitlabhq,dwrensha/gitlabhq,martinma4/gitlabhq,copystudy/gitlabhq,icedwater/gitlabhq,bozaro/gitlabhq,julianengel/gitlabhq,dreampet/gitlab,Razer6/gitlabhq,WSDC-NITWarangal/gitlabhq,LUMC/gitlabhq,Kambda/Mobbr,jrjang/gitlabhq,ibiart/gitlabhq