Automatic merge from submit-queue (batch tested with PRs 48494, 48733)
Move test-webserver from contrib/for-demos to kubernetes/test/images
**What this PR does / why we need it**:
This PR is for
- Moving the https://github.com/kubernetes/contrib/tree/master/for-demos/test-webserver to kubernetes/test/images - Refer https://github.com/kubernetes/contrib/pull/2544 for more information
- Multi architecture support for test-webserver image
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #
**Special notes for your reviewer**:
**Release note**:
```release-note
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