Automatic merge from submit-queue. 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>.
Bump pause container used by kubelet and tests to 3.1
This updates the version of the pause container used by the kubelet and
various test utilities to 3.1.
**What this PR does / why we need it**: The pause container hasn't been rebuilt in quite a while and needs an update to reap zombies (#50865) and for schema2 manifest (#56253).
**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes#50865, Fixes#56253
**Special notes for your reviewer**:
**Release note**:
```release-note
The kubelet uses a new release 3.1 of the pause container with the Docker runtime. This version will clean up orphaned zombie processes that it inherits.
```
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