Automatic merge from submit-queue (batch tested with PRs 48264, 48324, 48125, 47944, 47489)

Add Pod UID (metadata.uid) to downward API env var

**What this PR does / why we need it**:
Exposing Pod UID by downward API.

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #28918 

**Special notes for your reviewer**:
Generated files aren't committed. I'd like CI to tell me what scripts should I run to generate these files.

/cc @smarterclayton @vishh @dubstack

**Release note**:

```release-note
NONE
```