Enable Rubocop on lib/gitlab

This should wrap up frozen string
enablement for gitlab-ce.

xref gitlab-org/gitlab-ce#47424.

.rubocop.yml

@@ -50,7 +50,6 @@ Style/FrozenStringLiteralComment:
     - 'danger/**/*'
     - 'db/**/*'
     - 'ee/**/*'
-    - 'lib/gitlab/**/*'
     - 'lib/tasks/**/*'
     - 'qa/**/*'
     - 'rubocop/**/*'

changelogs/unreleased/frozen-string-lib-rubocop.yml

+---
+title: Enable Rubocop on lib/gitlab
+merge_request:
+author: gfyoung
+type: other