Merge pull request #47881 from cadmuxe/endpoint

Automatic merge from submit-queue (batch tested with PRs 47918, 47964, 48151, 47881, 48299)

Add ApiEndpoint support to GCE config.

**What this PR does / why we need it**:
Add the ability to change ApiEndpoint  for GCE.

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

**Special notes for your reviewer**:

**Release note**:
```release-note
None
```

hack/verify-flags/known-flags.txt

@@ -298,6 +298,7 @@ gather-logs-sizes
 gather-metrics-at-teardown
 gather-resource-usage
 gather-suite-metrics-at-teardown
+gce-api-endpoint
 gce-multizone
 gce-project
 gce-service-account