Merge pull request #55259 from ironcladlou/gc-partial-discovery

Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Tolerate partial discovery in garbage collector

Allow the garbage collector to tolerate partial discovery failures. On a
partial failure, use whatever was discovered, log the failures, and
allow the resync logic to try again later.

Fixes #55022.

```release-note
API discovery failures no longer crash the kube controller manager via the garbage collector.
```

/cc @caesarxuchao

test/integration/garbagecollector/garbage_collector_test.go

@@ -233,10 +233,7 @@ func setup(t *testing.T, workerCount int) *testContext {
 	discoveryClient := cacheddiscovery.NewMemCacheClient(clientSet.Discovery())
 	restMapper := discovery.NewDeferredDiscoveryRESTMapper(discoveryClient, meta.InterfacesForUnstructured)
 	restMapper.Reset()
-	deletableResources, err := garbagecollector.GetDeletableResources(discoveryClient)
-	if err != nil {
-		t.Fatalf("unable to get deletable resources: %v", err)
-	}
+	deletableResources := garbagecollector.GetDeletableResources(discoveryClient)
 	config := *masterConfig
 	config.ContentConfig = dynamic.ContentConfig()
 	metaOnlyClientPool := dynamic.NewClientPool(&config, restMapper, dynamic.LegacyAPIPathResolverFunc)