Increased performance of GL dropdown renderItem
Increased performance of GL dropdown renderItem

- Fixes an issue where `renderItem` is called several times even when
  not required
- Increased performance when rendering dropdown items

Closes #21110

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