Automatic merge from submit-queue
rkt: Force `rkt fetch` to fetch from remote to conform the image pull policy.
Fix https://github.com/kubernetes/kubernetes/issues/27646
Use `--no-store` option for `rkt fetch` to force it to fetch from remote.
However, `--no-store` will fetch the remote image regardless of whether the content of the image has changed or not.
This causes performance downgrade when the image tag is ':latest' and the image pull policy is 'always'.
The issue is tracked in https://github.com/coreos/rkt/issues/2937.
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