Reduce noise in cluster cleanup workers

Reduces failures due to unrecoverable, safe to ignore, "user errors".

See https://gitlab.com/gitlab-org/gitlab/-/issues/342923

Changelog: fixed

app/models/clusters/cluster.rb

@@ -309,7 +309,7 @@ module Clusters
     end
 
     def kubeclient
-      platform_kubernetes.kubeclient if kubernetes?
+      platform_kubernetes&.kubeclient if kubernetes?
     end
 
     def elastic_stack_adapter

app/services/clusters/cleanup/project_namespace_service.rb

@@ -35,9 +35,11 @@ module Clusters
       end
 
       def kubeclient_delete_namespace(kubernetes_namespace)
-        cluster.kubeclient.delete_namespace(kubernetes_namespace.namespace)
+        cluster.kubeclient&.delete_namespace(kubernetes_namespace.namespace)
       rescue Kubeclient::ResourceNotFoundError
-        # no-op: nothing to delete
+        # The resources have already been deleted, possibly on a previous attempt that timed out
+      rescue Gitlab::UrlBlocker::BlockedUrlError
+        # User gave an invalid cluster from the start, or deleted the endpoint before this job ran
       end
     end
   end

app/services/clusters/cleanup/service_account_service.rb

@@ -16,11 +16,14 @@ module Clusters
       def delete_gitlab_service_account
         log_event(:deleting_gitlab_service_account)
 
-        cluster.kubeclient.delete_service_account(
+        cluster.kubeclient&.delete_service_account(
           ::Clusters::Kubernetes::GITLAB_SERVICE_ACCOUNT_NAME,
           ::Clusters::Kubernetes::GITLAB_SERVICE_ACCOUNT_NAMESPACE
         )
       rescue Kubeclient::ResourceNotFoundError
+        # The resources have already been deleted, possibly on a previous attempt that timed out
+      rescue Gitlab::UrlBlocker::BlockedUrlError
+        # User gave an invalid cluster from the start, or deleted the endpoint before this job ran
       end
     end
   end

spec/services/clusters/cleanup/project_namespace_service_spec.rb

@@ -58,6 +58,19 @@ RSpec.describe Clusters::Cleanup::ProjectNamespaceService do
 
         subject
       end
+
+      context 'when cluster.kubeclient is nil' do
+        let(:kubeclient_instance_double) { nil }
+
+        it 'schedules ::ServiceAccountWorker' do
+          expect(Clusters::Cleanup::ServiceAccountWorker).to receive(:perform_async).with(cluster.id)
+          subject
+        end
+
+        it 'deletes namespaces from database' do
+          expect { subject }.to change { cluster.kubernetes_namespaces.exists? }.from(true).to(false)
+        end
+      end
     end
 
     context 'when cluster has no namespaces' do

spec/services/clusters/cleanup/service_account_service_spec.rb

@@ -44,5 +44,13 @@ RSpec.describe Clusters::Cleanup::ServiceAccountService do
     it 'deletes cluster' do
       expect { subject }.to change { Clusters::Cluster.where(id: cluster.id).exists? }.from(true).to(false)
     end
+
+    context 'when cluster.kubeclient is nil' do
+      let(:kubeclient_instance_double) { nil }
+
+      it 'deletes cluster' do
+        expect { subject }.to change { Clusters::Cluster.where(id: cluster.id).exists? }.from(true).to(false)
+      end
+    end
   end
 end