Automatic merge from submit-queue (batch tested with PRs 42379, 42668, 42876, 41473, 43260)
Bump test coverage for initialresources
**What this PR does / why we need it**:
Increases test coverage for `plugin/pkg/admission/initialresources` to 80.2%.
**Which issue this PR fixes**
https://github.com/kubernetes/kubernetes/issues/39559
**Special notes for your reviewer**:
Some of these features require E2E tests to achieve 100% coverage, the tests here are just unit tests, so I've tried to delineate as much as possible. I also saw that we might be exporting a lot of this to Heapster in the future.
**Release note**:
```release-note
Test coverage for initialresources increased to 80.2% percent.
```
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