Automatic merge from submit-queue (batch tested with PRs 67161, 67093, 67077). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Graduate ResourceQuotaScopeSelectors to beta
All the pre-requisite items listed in the tracker issue, https://github.com/kubernetes/kubernetes/issues/66673, have got merged. Therefore, opening this PR to graduate scope selectors field in the resource quota spec.
**Release note**:
```release-note
Graduate Resource Quota ScopeSelectors to beta, and enable it by default.
```
/cc @derekwaynecarr @deads2k @smarterclayton
a1b3133b46