Add rubocop for deprecated advanced search migrations

What does this MR do and why?

Related to #412676 (closed)

There is a comment in the migration to not use it to gate code with has_migration_finished?, but I thought a rubocop might be beter (and would allow us to prevent other migrations from being used in the future)

Issue to remove grace period: #415924 (closed)

Screenshots or screen recordings

N/A

How to set up and validate locally

1. add code to check migration_has_finished? for

diff --git a/ee/lib/elastic/latest/project_instance_proxy.rb b/ee/lib/elastic/latest/project_instance_proxy.rb
index 081bb9ce4f3e..a55ec9cf5134 100644
--- a/ee/lib/elastic/latest/project_instance_proxy.rb
+++ b/ee/lib/elastic/latest/project_instance_proxy.rb
@@ -45,7 +45,7 @@ def as_indexed_json(options = {})

         data['traversal_ids'] = target.elastic_namespace_ancestry

-        if ::Elastic::DataMigrationService.migration_has_finished?(:add_ci_catalog_to_project)
+        if ::Elastic::DataMigrationService.migration_has_finished?(:add_ci_catalog_to_project) && ::Elastic::DataMigrationService.migration_has_finished?(:backfill_project_permissions_in_blobs_using_permutations)
           data['ci_catalog'] = target.catalog_resource.present?
         end

2. run rubocop and verify it reports the issue: rubocop ee/lib/elastic/latest/project_instance_proxy.rb
3. I also tested without the :: to make sure it worked

MR acceptance checklist

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