Mark `Projects::OverwriteProjectService#destroy_old_project` cross-DB

It appears that `#destroy_old_project` does `Project.transaction`
which makes `Projects::DestroyService#delete_ci_records!` to run
in a transaction.

app/services/projects/overwrite_project_service.rb

@@ -11,7 +11,9 @@ module Projects
         move_before_destroy_relationships(source_project)
         # Reset is required in order to get the proper
         # uncached fork network method calls value.
-        destroy_old_project(source_project.reset)
+        ::Gitlab::Database::QueryAnalyzers::PreventCrossDatabaseModification.allow_cross_database_modification_within_transaction(url: 'https://gitlab.com/gitlab-org/gitlab/-/issues/340256') do
+          destroy_old_project(source_project.reset)
+        end
         rename_project(source_project.name, source_project.path)
 
         @project

spec/support/database/cross-database-modification-allowlist.yml

@@ -8,4 +8,3 @@
 - "./spec/models/clusters/applications/runner_spec.rb"
 - "./spec/requests/api/commits_spec.rb"
 - "./spec/services/ci/retry_build_service_spec.rb"
-- "./spec/services/projects/overwrite_project_service_spec.rb"