Add helpers to exactly undo cleanup_concurrent_column_rename

What does this MR do?

Create helpers to undo cleanup_concurrent_column_rename and rename_column_concurrently.

The current practice of using cleanup_concurrent_column_rename in the down method of a migration that calls rename_column_concurrently does not work well (see https://gitlab.com/gitlab-org/gitlab-ee/issues/13772#note_207734364).

EE MR: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/15614

Issue: https://gitlab.com/gitlab-org/gitlab-ee/issues/13772

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry for user-facing changes, or community contribution. Check the link for other scenarios.
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team