Automatic merge from submit-queue (batch tested with PRs 41297, 42638, 42666, 43039, 42567)

Delete offline restclient from clusterKubeClientMap

When federation controller manager checks cluster status, it will
delete the offline cluster from clusterSet, but do not delete the
corresponding restclient from the map clusterKubeClientMap for
the offline cluster. This patch can fix it.



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

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #

**Special notes for your reviewer**:

**Release note**:

```release-note
```