Automatic merge from submit-queue (batch tested with PRs 45766, 46223)
Scheduler should use a shared informer, and fix broken watch behavior for cached watches
Can be used either from a true shared informer or a local shared
informer created just for the scheduler.
Fixes a bug in the cache watcher where we were returning the "current" object from a watch event, not the historic event. This means that we broke behavior when introducing the watch cache. This may have API implications for filtering watch consumers - but on the other hand, it prevents clients filtering from seeing objects outside of their watch correctly, which can lead to other subtle bugs.
```release-note
The behavior of some watch calls to the server when filtering on fields was incorrect. If watching objects with a filter, when an update was made that no longer matched the filter a DELETE event was correctly sent. However, the object that was returned by that delete was not the (correct) version before the update, but instead, the newer version. That meant the new object was not matched by the filter. This was a regression from behavior between cached watches on the server side and uncached watches, and thus broke downstream API clients.
```
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