ignore hashed repositories when doing rake gitlab:cleanup:dirs

Closes #40352

See merge request gitlab-org/gitlab-ce!15600

(cherry picked from commit 815f35be)

17069a95 ignore hashed repositories when doing rake gitlab:cleanup:dirs
9fddca65 added changelog
02dd3b4e static analysis fix
3bb103f2 refactored the hashed repository name
30a9fc33 static-analysis fix