Automatic merge from submit-queue (batch tested with PRs 41937, 41151, 42092, 40269, 42135)
Improve code coverage for scheduler/algorithmprovider/defaults
**What this PR does / why we need it**:
Improve code coverage for scheduler/algorithmprovider/defaults from #39559
Thanks for your review.
**Special notes for your reviewer**:
**Release note**:
```release-note
```
Where possible, switch the scheduler to use generated listers and
informers. There are still some places where it probably makes more
sense to use one-off reflectors/informers (listing/watching just a
single node, listing/watching scheduled & unscheduled pods using a field
selector).
