Use patch instead of update to alleviate HRA conflict on webhook (#358)

We sometimes see that integration test fails due to runner replicas not meeting the expected number in a timely manner. After investigating a bit, this turned out to be due to that HRA updates on webhook-based autoscaler and HRA controller are conflicting. This changes the controllers to use Patch instead of Update to make conflicts less likely to happen.

I have also updated the hra controller to use Patch when updating RunnerDeployment, too.

Overall, these changes should make the webhook-based autoscaling more reliable due to less conflicts.

controllers/integration_test.go

@@ -244,6 +244,7 @@ var _ = Context("INTEGRATION: Inside of a new namespace", func() {
 
 				ExpectRunnerSetsCountEventuallyEquals(ctx, ns.Name, 1)
 				ExpectRunnerSetsManagedReplicasCountEventuallyEquals(ctx, ns.Name, 3)
+				ExpectHRAStatusCacheEntryLengthEventuallyEquals(ctx, ns.Name, name, 1)
 			}
 
 			{
@@ -601,6 +602,21 @@ var _ = Context("INTEGRATION: Inside of a new namespace", func() {
 	})
 })
 
+func ExpectHRAStatusCacheEntryLengthEventuallyEquals(ctx context.Context, ns string, name string, value int, optionalDescriptions ...interface{}) {
+	EventuallyWithOffset(
+		1,
+		func() int {
+			var hra actionsv1alpha1.HorizontalRunnerAutoscaler
+
+			err := k8sClient.Get(ctx, types.NamespacedName{Namespace: ns, Name: name}, &hra)
+
+			ExpectWithOffset(1, err).NotTo(HaveOccurred(), "failed to get test HRA resource")
+
+			return len(hra.Status.CacheEntries)
+		},
+		time.Second*5, time.Millisecond*500).Should(Equal(value), optionalDescriptions...)
+}
+
 func ExpectHRADesiredReplicasEquals(ctx context.Context, ns, name string, desired int, optionalDescriptions ...interface{}) {
 	var rd actionsv1alpha1.HorizontalRunnerAutoscaler