Automatic merge from submit-queue (batch tested with PRs 49847, 49743, 49853, 50225, 50479)
Add node benchmark tests for cos-m60 with docker 1.12.6
Ref: https://github.com/kubernetes/kubernetes/issues/42926
This PR adds a benchmark tests against cos-m60 with docker 1.12.6 on http://node-perf-dash.k8s.io. This test is useful for docker validation -- we can compare the performance of different dockers on the same OS.
cos-m60 comes with docker 1.13.1 by default, so we need to use cloud-init to downgrade the version to 1.12.6.
**Release note**:
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/assign @dchen1107