fix rubocop errors and ensure prometheus_installed? doesn't fail in CI tests where project is nil
fix rubocop errors and ensure prometheus_installed? doesn't fail in CI tests where project is nil

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