Automatic merge from submit-queue (batch tested with PRs 46252, 45524, 46236, 46277, 46522)

Add /healthz back to kube-proxy metrics server

Fixes #46447.

/healthz is removed from kube-proxy metrics server by #44968 and that breaks our upgrade test, which run 1.6 tests on 1.7 cluster. It seems harmless to continue holding /healthz on metrics server as well, so that we won't break other potential users.

/assign @bowei 
cc @dchen1107 

**Release note**:

```release-note
NONE
```