Failure in QA specs on staging due to Praefect issue

Pipeline: https://ops.gitlab.net/gitlab-org/quality/staging/pipelines/89125

All tests failed on staging due to some issue with quality+qa_bot@gitlab.com authorization - after user is authorized, dashboard page returns 500 error.

Sentry error log: https://sentry.gitlab.net/gitlab/staginggitlabcom/issues/1035268/?query=is:unresolved

ActionView::Template::ErrorRootController#index
error3:only messages for praefect are allowed

Discussions here: https://gitlab.slack.com/archives/C3ER3TQBT/p1572293689252600