Automatic merge from submit-queue. 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>.

[e2e service] Fix CleanupGCEResources for regional test

*What this PR does / why we need it**:
From https://k8s-testgrid.appspot.com/google-gke-staging#gke-staging-1-8-1-9-upgrade-regional-cluster&width=20, regional cluster test is failing because the GCE resource cleanup function attempts to parse region from `--gcp-zone` while regional cluster only set `--gcp-region`.

This PR pipes region into the cleanup function as well. This will need to be cherrypicked to 1.8 and 1.9.

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #NONE 

**Special notes for your reviewer**:
/assign @bowei @wojtek-t 
cc @nikhiljindal to see if there is anything should be fixed for federation.

**Release note**:

```release-note
NONE
```