What does this MR do and why?

In this merge request, we are adding a new cop to validate the introduced_by_url url (batched background migrations dictionary).

We need to have this link in the proper format because we will have a job that will extract the merge request ID from the link. More info here: gitlab-org/database-team/gitlab-com-database-testing!172 (comment 1658600386)

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #432943 (closed)