Automatic merge from submit-queue (batch tested with PRs 57906, 57425, 56939, 57317, 57762). 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>.

cluster/gce/gci: Support passing kube-scheduler policy config

**What this PR does / why we need it**:

This allows us to specify a customized scheduler policy configuration.

**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 #

**Special notes for your reviewer**:

I'm aware of the ConfigMap but passing a file is much simpler in our case.

This PR is low risk, we will want to cherry pick this into 1.9.

**Release note**:

```release-note
None
```