Automatic merge from submit-queue (batch tested with PRs 67377, 67801). 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>.
Revert "Parallelize RC deletion in density test"
Reverts kubernetes/kubernetes#67712
2k test has failed because of this: even if we trigger removal in parallel, controller manager is deleting replicacontrollers sequentially:
```
I0823 13:35:41.906] Aug 23 13:35:41.906: INFO: Terminating { ReplicationController} density43650-0-584f5bb0-a6d6-11e8-b145-0a580a3c6f08 pods took: 1m0.00118401s
I0823 13:36:42.021] Aug 23 13:36:42.020: INFO: Terminating { ReplicationController} density43650-14-584f5bb0-a6d6-11e8-b145-0a580a3c6f08 pods took: 2m0.00202238s
I0823 13:37:42.056] Aug 23 13:37:42.055: INFO: Terminating { ReplicationController} density43650-8-584f5bb0-a6d6-11e8-b145-0a580a3c6f08 pods took: 3m0.004624139s
I0823 13:38:42.092] Aug 23 13:38:42.092: INFO: Terminating { ReplicationController} density43650-5-584f5bb0-a6d6-11e8-b145-0a580a3c6f08 pods took: 4m0.000797258s
I0823 13:39:32.095] Aug 23 13:39:32.095: INFO: Terminating { ReplicationController} density43650-4-584f5bb0-a6d6-11e8-b145-0a580a3c6f08 pods took: 4m50.000689353s
I0823 13:40:32.206] Aug 23 13:40:32.206: INFO: Terminating { ReplicationController} density43650-11-584f5bb0-a6d6-11e8-b145-0a580a3c6f08 pods took: 5m50.000731007s
I0823 13:41:32.206] Aug 23 13:41:32.206: INFO: Terminating { ReplicationController} density43650-7-584f5bb0-a6d6-11e8-b145-0a580a3c6f08 pods took: 6m50.000648956s
I0823 13:42:32.194] Aug 23 13:42:32.194: INFO: Terminating { ReplicationController} density43650-12-584f5bb0-a6d6-11e8-b145-0a580a3c6f08 pods took: 7m50.001155426s
I0823 13:43:32.282] Aug 23 13:43:32.282: INFO: Terminating { ReplicationController} density43650-10-584f5bb0-a6d6-11e8-b145-0a580a3c6f08 pods took: 8m50.000739417s
I0823 13:44:16.434] W0823 13:44:16.433780 7517 reflector.go:270] k8s.io/kubernetes/test/utils/pod_store.go:56: watch of *v1.Pod ended with: too old resource version: 624915 (659380)
I0823 13:44:32.282] Aug 23 13:44:32.282: INFO: Terminating { ReplicationController} density43650-9-584f5bb0-a6d6-11e8-b145-0a580a3c6f08 pods took: 9m50.000486689s
I0823 13:44:42.283] Aug 23 13:44:42.282: INFO: Unexpected error occurred: error while waiting for pods to become inactive density43650-2-584f5bb0-a6d6-11e8-b145-0a580a3c6f08: timed out waiting for the condition
I0823 13:44:42.331] Aug 23 13:44:42.331: INFO: Unexpected error occurred: error while waiting for pods to become inactive density43650-1-584f5bb0-a6d6-11e8-b145-0a580a3c6f08: timed out waiting for the condition
I0823 13:44:42.333] Aug 23 13:44:42.332: INFO: Unexpected error occurred: error while waiting for pods to become inactive density43650-6-584f5bb0-a6d6-11e8-b145-0a580a3c6f08: timed out waiting for the condition
I0823 13:44:42.334] Aug 23 13:44:42.333: INFO: Unexpected error occurred: error while waiting for pods to become inactive density43650-13-584f5bb0-a6d6-11e8-b145-0a580a3c6f08: timed out waiting for the condition
I0823 13:44:42.437] Aug 23 13:44:42.436: INFO: Unexpected error occurred: error while waiting for pods to become inactive density43650-3-584f5bb0-a6d6-11e8-b145-0a580a3c6f08: timed out waiting for the condition
```
5103bd6a53