Automatic merge from submit-queue (batch tested with PRs 52485, 52443, 52597, 52450, 51971). 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>..

Removing PrometheusPushGateway --prom-push-gateway flag from e2e tests.

**What this PR does / why we need it**: Removing obsolete PrometheusPushGateway --prom-push-gateway flag from e2e tests.

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #45947

**Special notes for your reviewer**:

**Release note**:

```release-note
Removing `--prom-push-gateway` flag from e2e tests
```