Backport `AutocompleteController#load_project` from EE!581.
Backport `AutocompleteController#load_project` from EE!581.

- This is an optimization that was made in !581, and it needs to be
  backported to CE to avoid merge conflicts in the future.

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