Remove `Note#system?` "override"
Remove `Note#system?` "override"

This method was duplicating default Rails behavior.

allysonbarros/gitlabhq,axilleas/gitlabhq,jirutka/gitlabhq,jirutka/gitlabhq,htve/GitlabForChinese,mr-dxdy/gitlabhq,iiet/iiet-git,dplarson/gitlabhq,icedwater/gitlabhq,htve/GitlabForChinese,iiet/iiet-git,Soullivaneuh/gitlabhq,SVArago/gitlabhq,screenpages/gitlabhq,dreampet/gitlab,LUMC/gitlabhq,larryli/gitlabhq,ttasanen/gitlabhq,dplarson/gitlabhq,axilleas/gitlabhq,martijnvermaat/gitlabhq,daiyu/gitlab-zh,mmkassem/gitlabhq,icedwater/gitlabhq,dwrensha/gitlabhq,LUMC/gitlabhq,Soullivaneuh/gitlabhq,jirutka/gitlabhq,allysonbarros/gitlabhq,t-zuehlsdorff/gitlabhq,screenpages/gitlabhq,shinexiao/gitlabhq,stoplightio/gitlabhq,Soullivaneuh/gitlabhq,t-zuehlsdorff/gitlabhq,daiyu/gitlab-zh,martijnvermaat/gitlabhq,jirutka/gitlabhq,stoplightio/gitlabhq,allysonbarros/gitlabhq,dreampet/gitlab,htve/GitlabForChinese,dplarson/gitlabhq,dreampet/gitlab,SVArago/gitlabhq,dreampet/gitlab,SVArago/gitlabhq,martijnvermaat/gitlabhq,LUMC/gitlabhq,axilleas/gitlabhq,daiyu/gitlab-zh,iiet/iiet-git,shinexiao/gitlabhq,Soullivaneuh/gitlabhq,screenpages/gitlabhq,icedwater/gitlabhq,larryli/gitlabhq,LUMC/gitlabhq,openwide-java/gitlabhq,ttasanen/gitlabhq,openwide-java/gitlabhq,daiyu/gitlab-zh,openwide-java/gitlabhq,larryli/gitlabhq,htve/GitlabForChinese,shinexiao/gitlabhq,t-zuehlsdorff/gitlabhq,mmkassem/gitlabhq,darkrasid/gitlabhq,allysonbarros/gitlabhq,ttasanen/gitlabhq,larryli/gitlabhq,dwrensha/gitlabhq,shinexiao/gitlabhq,mr-dxdy/gitlabhq,SVArago/gitlabhq,darkrasid/gitlabhq,mr-dxdy/gitlabhq,ttasanen/gitlabhq,dwrensha/gitlabhq,icedwater/gitlabhq,dplarson/gitlabhq,t-zuehlsdorff/gitlabhq,mmkassem/gitlabhq,axilleas/gitlabhq,screenpages/gitlabhq,darkrasid/gitlabhq,stoplightio/gitlabhq,mr-dxdy/gitlabhq,darkrasid/gitlabhq,stoplightio/gitlabhq,mmkassem/gitlabhq,dwrensha/gitlabhq,openwide-java/gitlabhq,martijnvermaat/gitlabhq,iiet/iiet-git