Merge pull request #24647 from yifan-gu/rkt_gc

Automatic merge from submit-queue

rkt: Refactor GarbageCollect to enforce GCPolicy.

Previously, we uses `rkt gc` to garbage collect dead pods, which is very coarse, and can cause the dead pods to be removed too aggressively. 

This PR improves the garbage collection, now after one GC iteration:
- The deleted pods will be removed.
- If the number of containers exceeds gcPolicy.MaxContainers,
  then containers whose ages are older than gcPolicy.minAge will be removed.

cc @kubernetes/sig-node @euank @sjpotter 

Pending on #23887 for the Godep updates.

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cmd/integration/integration.go

@@ -230,7 +230,7 @@ func startComponents(firstManifestURL, secondManifestURL string) (string, string
 		cadvisorInterface,
 		configFilePath,
 		nil,
-		containertest.FakeOS{},
+		&containertest.FakeOS{},
 		1*time.Second,  /* FileCheckFrequency */
 		1*time.Second,  /* HTTPCheckFrequency */
 		10*time.Second, /* MinimumGCAge */
@@ -263,7 +263,7 @@ func startComponents(firstManifestURL, secondManifestURL string) (string, string
 		cadvisorInterface,
 		"",
 		nil,
-		containertest.FakeOS{},
+		&containertest.FakeOS{},
 		1*time.Second,  /* FileCheckFrequency */
 		1*time.Second,  /* HTTPCheckFrequency */
 		10*time.Second, /* MinimumGCAge */