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Update kubectl to the stable version

**What this PR does / why we need it**:
Update kubectl to the stable version 1.8.1
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #
fixes #54762
**Special notes for your reviewer**:

**Release note**:

```
Update kubectl in the addon-manager to v1.8.4
```