Acknowledge `applications/runner_spec.rb` cross-DB modification

Ensure that `applications/runner_spec.rb` is properly covered with
cross-DB and removed from the allowlist.

app/models/clusters/applications/runner.rb

@@ -41,7 +41,9 @@ module Clusters
       end
 
       def prepare_uninstall
-        runner&.update!(active: false)
+        ::Gitlab::Database::QueryAnalyzers::PreventCrossDatabaseModification.allow_cross_database_modification_within_transaction(url: 'https://gitlab.com/gitlab-org/gitlab/-/issues/350180') do
+          runner&.update!(active: false)
+        end
       end
 
       def post_uninstall

spec/factories/clusters/applications/helm.rb

@@ -118,7 +118,6 @@ FactoryBot.define do
     end
 
     factory :clusters_applications_runner, class: 'Clusters::Applications::Runner' do
-      runner factory: %i(ci_runner)
       cluster factory: %i(cluster with_installed_helm provided_by_gcp)
     end
 

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

 - "./spec/lib/gitlab/ci/pipeline/chain/create_spec.rb"
 - "./spec/models/ci/build_trace_chunk_spec.rb"
 - "./spec/models/ci/job_artifact_spec.rb"
-- "./spec/models/clusters/applications/runner_spec.rb"
 - "./spec/services/ci/retry_build_service_spec.rb"