Automatic merge from submit-queue (batch tested with PRs 51335, 51364, 51130, 48075, 50920)
Change default validation to openapi
**What this PR does / why we need it**:
And also update the test to match the new error string.
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes https://github.com/kubernetes/kubectl/issues/49
**Special notes for your reviewer**:
**Release note**:
```release-note
Performs validation (when applying for example) against OpenAPI schema rather than Swagger 1.0.
```
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