Automatic merge from submit-queue (batch tested with PRs 42940, 42906, 42970, 42848)

Move node and event observer helpers to e2e/common

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

Moves existing test helper functions in OIR e2e tests to `test/e2e/common`. These functions wrap informers to help test writers to observe events instead of long-polling for status updates.

For usage examples, see `test/e2e/opaque_resource.go`.

cc @kubernetes/sig-scheduling-misc

**Release note**:
```release-note
NONE
```