Automatic merge from submit-queue (batch tested with PRs 41714, 41510, 42052, 41918, 31515)

Switch scheduler to use generated listers/informers

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).

I think this can wait until master is open for 1.7 pulls, given that we're close to the 1.6 freeze.

After this and #41482 go in, the only code left that references legacylisters will be federation, and 1 bit in a stateful set unit test (which I'll clean up in a follow-up).

@resouer I imagine this will conflict with your equivalence class work, so one of us will be doing some rebasing 😄 

cc @wojtek-t @gmarek  @timothysc @jayunit100 @smarterclayton @deads2k @liggitt @sttts @derekwaynecarr @kubernetes/sig-scheduling-pr-reviews @kubernetes/sig-scalability-pr-reviews