Mark RemoveApplicationSettingsAiAccessTokenColumn as no-op

What does this MR do and why?

This MR marks the RemoveApplicationSettingsAiAccessTokenColumn migration as no-op and reverts the structure to pre-removal MR. This is part of the Corrective action: https://gitlab.com/gitlab-com/gl-infra/reliability/-/issues/24523

Original MR: !132635 (merged)

I followed this procedure https://docs.gitlab.com/ee/development/database/deleting_migrations.html

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: #427695 (closed)

Corrective action: https://gitlab.com/gitlab-com/gl-infra/reliability/-/issues/2452