Revert "Merge branch 'mo-add-codequality-feature-flag' into 'master'"

This reverts merge request !47938

config/feature_flags/development/codequality_mr_diff.yml

----
-name: codequality_mr_diff
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/47938
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/284140
-milestone: '13.7'
-type: development
-group: group::testing
-default_enabled: false