Automatic merge from submit-queue

cluster/gce/coreos: Update heapster apiVersion

This fixes an inadvertant search-replace error in #26617.
The error was missed then because the search-replace issue wasn't
present in the standalone controllers, but was in all the others.

I verified that with this change heapster comes up under the default influxdb monitoring and without this change addon manager spits out validation failure errors for the heapster yaml.

cc @yifan-gu