Automatic merge from submit-queue (batch tested with PRs 44625, 43594, 44756, 44730)

Check for terminating Pod prior to launching successor in StatefulSet

Modifies sync loop for StatefulSet controller to check if a Pod is terminating before launching its successor. Fixes #44229. Should be cherry picked into 1.6 branch.

**Which issue this PR fixes**
fixes #44229 

```release-note
NONE
```