Move RefService#DeleteBranch to OPT_OUT
Move RefService#DeleteBranch to OPT_OUT

Part of: gitlab-org/gitaly#546

axilleas/gitlabhq,iiet/iiet-git,dreampet/gitlab,axilleas/gitlabhq,mmkassem/gitlabhq,dreampet/gitlab,axilleas/gitlabhq,iiet/iiet-git,iiet/iiet-git,stoplightio/gitlabhq,stoplightio/gitlabhq,jirutka/gitlabhq,dreampet/gitlab,dreampet/gitlab,jirutka/gitlabhq,stoplightio/gitlabhq,axilleas/gitlabhq,mmkassem/gitlabhq,mmkassem/gitlabhq,jirutka/gitlabhq,jirutka/gitlabhq,mmkassem/gitlabhq,iiet/iiet-git,stoplightio/gitlabhq