Automatic merge from submit-queue (batch tested with PRs 41037, 40118, 40959, 41084, 41092)

Switch CSR controller to use shared informer

Switch the CSR controller to use a shared informer. Originally part of #40097 but I'm splitting that up into multiple PRs.

I have added a test to try to ensure we don't mutate the cache. It could use some fleshing out for additional coverage but it gets the initial job done, I think.

cc @mikedanese @deads2k @liggitt @sttts @kubernetes/sig-scalability-pr-reviews