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kube-proxy: Fix flag validation for healthz-bind-address and metrics-bind-address
**What this PR does / why we need it**: `--healthz-bind-address` and `--metrics-bind-address` are broken for kube-proxy as they do not allow `ip:port` format, though they claim to support it.
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: Fixes#53754
**Special notes for your reviewer**:
cc @ncdc
**Release note**:
```release-note
Fix kube-proxy flags validation for --healthz-bind-address and --metrics-bind-address to allow specifying ip:port.
```