[9.3] Revert "Merge branch 'mk-toggle-writing-to-auth-keys-1631' into 'master'"
Reverts https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/2004 because of https://gitlab.com/gitlab-org/gitlab-ee/issues/2738.
Proper fix on the works in https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/2240.