Disable the inheritance column of services in DisableInvalidServiceTemplates migration

What does this MR do?

The commit message explains what this is fixing. Note that if you upgrade to 8.17.0 first and then to 8.17.1, you don't experience the failure because db/post_migrate/20170214111112_delete_deprecated_gitlab_ci_service.rb was added in 8.17.0 and deletes the GitlabCiService legacy service, but db/post_migrate/20170211073944_disable_invalid_service_templates.rb was added in 8.17.1 with a smaller timestamp than db/post_migrate/20170214111112_delete_deprecated_gitlab_ci_service.rb, thus db:migrate would first try to migrate this one bu would fail (because STI was not disabled) on any remaining GitlabCiService since it's not yet removed from the DB at this point.

Does this MR meet the acceptance criteria?

• Changelog entry added
• Tests
  • All builds are passing
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #28850 (closed)