Automatic merge from submit-queue (batch tested with PRs 53477, 53614). 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>.

Fix potential problem when scaling --replicas=0

**What this PR does / why we need it**:

We have defensive code for checking if newRS != nil for
DeploymentProgressing and DeploymentTimedOut but not for
DeploymentComplete. Let's add the check here as well as
this problem was seen in the wild.

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

Fixes #53613 

**Special notes for your reviewer**:

**Release note**:

```release-note
NONE
```