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Increase Horizontal Pod Autoscaler update frequency to every 15s
**What this PR does / why we need it**:
PR increases Horizontal Pod Autoscaler default update interval (30s -> 15s). It will improve HPA reaction time for metric changes.
**Release note**:
```release-note
Increase Horizontal Pod Autoscaler default update interval (30s -> 15s). It will improve HPA reaction time for metric changes.
```