Turn on rubocop for frozen string in ee/

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/47424.

.rubocop.yml

@@ -49,7 +49,9 @@ Style/FrozenStringLiteralComment:
     - 'config/**/*'
     - 'danger/**/*'
     - 'db/**/*'
-    - 'ee/**/*'
+    - 'ee/db/**/*'
+    - 'ee/spec/**/*'
+    - 'ee/lib/tasks/**/*'
     - 'lib/tasks/**/*'
     - 'qa/**/*'
     - 'rubocop/**/*'

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

+---
+title: Turn on rubocop for frozen string in ee/
+merge_request:
+author: gfyoung
+type: other