Automatic merge from submit-queue (batch tested with PRs 56021, 55843, 55088, 56117, 55859). 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>.

Fix panic when AlphaFeatureGate isn't configured for gcp.

**What this PR does / why we need it**:
When AlphaFeatureGate isn't configured, the pointer will be nil. This PR fixes it.

**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 #56009

**Special notes for your reviewer**:
cc @jsiebens 

**Release note**:

```release-note
NONE
```