Automatic merge from submit-queue (batch tested with PRs 59367, 60007). 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>.

podtolerationrestriction: fix informer race in test

**What this PR does / why we need it**: This fixes test flakes in the PodTolerationRestriction admission controller unit tests. They seem to pass most of the time currently, but modifications I was making for #58818 changed timing and caused it to constantly break.

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

**Special notes for your reviewer**: n/a

Sending this as a one-off because the changes for both of the admin controllers in #58818 require additional discussion. Thanks to @ericchiang for finding it and authoring the commit; I just rebased and sent the PR.

```release-note
NONE
```