Eliminate N+1 queries in LFS file locks checks during a push
This significantly improves performance when a user pushes many references. project.path_locks.any? doesn't cache the output and runs `SELECT 1 AS one FROM "path_locks" WHERE project_id = N` each time. When there are thousands of refs being pushed, this can time out the unicorn worker. CE port for https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/6159.
Showing with 44 additions and 1 deletion