Automatic merge from submit-queue (batch tested with PRs 50091, 50231, 50238, 50236, 50243)
Modify e2e.go to arbitrarily pick one of zones we have nodes in for multizone tests.
**What this PR does / why we need it**:
When e2e runs in multizone configuration, zone config property can be empty.
This PR, in that case, overrides an empty value with arbitrarily chosen zone that we have nodes in.
**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
```
969ae1ebee