Automatic merge from submit-queue (batch tested with PRs 48381, 48274)

Fix completions for --namespace to override kubectl flags

**What this PR does / why we need it**:
This PR fixes completions for --namespace to override kubectl flags. Due to not using __kubectl_parse_get, __kubectl_get_namespaces doesn't support to override kubectl flags.

**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
NONE
```