Automatic merge from submit-queue

Remove deprecated init-container in annotations

fixes #50655
fixes #51816 
closes #41004
fixes #51816 

Builds on #50654 and drops the initContainer annotations on conversion to prevent bypassing API server validation/security and targeting version-skewed kubelets that still honor the annotations

```release-note
The deprecated alpha and beta initContainer annotations are no longer supported. Init containers must be specified using the initContainers field in the pod spec.
```