Automatic merge from submit-queue (batch tested with PRs 46977, 47005, 47018, 47061, 46809)
Fix HostAlias to validate against DNS1123 hostname instead of just labels
**What this PR does / why we need it**: the validation for HostAlias was validating the hostnames against DNS labels instead of hostnames. This means hostnames like `foo.bar` would fail. I did not catch this because unit test cases only had hostnames like `foo`.
**Which issue this PR fixes**: fixes issue introduced in #44641
**Release note**:
```release-note
fixed HostAlias in PodSpec to allow `foo.bar` hostnames instead of just `foo` DNS labels.
```
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