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Change CPU sample sanitization in HPA.

**What this PR does / why we need it**:
Change CPU sample sanitization in HPA.
    Ignore samples if:
    - Pod is beeing initalized - 5 minutes from start defined by flag
        - pod is unready
        - pod is ready but full window of metric hasn't been colected since
        transition
    - Pod is initialized - 5 minutes from start defined by flag:
        - Pod has never been ready after initial readiness period.

**Release notes:**
```release-note
Improve CPU sample sanitization in HPA by taking metric's freshness into account.
```