Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

update apps/v1 types.go comments for controller spec selector fields

**What this PR does / why we need it**:
This PR updates apps/v1 types.go comments (including removal of `optional` tag) for controller spec selector fields.

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
xref #50808

**Release note**:

```release-note
NONE
```