Drop migration that finalizes migration to add PAT expiration

What does this MR do and why?

This MR drops the migration that finalizes a migration that added an expiration to all tokens that did not have one. Due to the impact on users, this drops the migration to avoid interruption to user workflows without them realizing it.

Note this only will help customers that have not already upgraded to GitLab 16.0. This finalize step will already be run for instances that have already upgraded to GitLab 16.7.

Related to https://gitlab.com/gitlab-org/gitlab/-/issues/462157

MR acceptance checklist

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

• This MR is backporting a bug fix, documentation update, or spec fix, previously merged in the default branch.
• The MR that fixed the bug on the default branch has been deployed to GitLab.com (not applicable for documentation or spec changes).
• This MR has a severity label assigned (if applicable).
• Set the milestone of the merge request to match the target backport branch version.
• This MR has been approved by a maintainer (only one approval is required).
• Ensure the e2e:package-and-test-ee job has either succeeded or been approved by a Software Engineer in Test.

Note to the merge request author and maintainer

If you have questions about the patch release process, please:

• Refer to the patch release runbook for engineers and maintainers for guidance.
• Ask questions on the #releases Slack channel (internal only).