Enable RSpec/AnyInstanceOf cop and move offenses to manual todo file

Prior this change we were introducing new offense without notice.

.rubocop.yml

@@ -438,9 +438,6 @@ Graphql/Descriptions:
     - 'app/graphql/**/*'
     - 'ee/app/graphql/**/*'
 
-RSpec/AnyInstanceOf:
-  Enabled: false
-
 # Cops for upgrade to gitlab-styles 3.1.0
 RSpec/ImplicitSubject:
   Enabled: false