Automatic merge from submit-queue
remove apps/v1beta2 defaulting codes for obj.Spec.Selector and obj.Labels
**What this PR does / why we need it**:
This PR removes defaulting codes for `obj.Spec.Selector`. Currently, `obj.Spec.Selector.MatchLabels` is set to `obj.Spec.Template.Labels` if `obj.Spec.Template.Labels != nil && obj.Spec.Selector == nil`. We should not perform this defaulting operation as controllers selectors are immutable.
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes#50339
**Special notes for your reviewer**:
This PR removes defaulting codes for `apps/v1beta2` only. The defaulting codes for validation will be removed in another PR.
**Release note**:
```NONE
```
17ec91c572