fix: fix waiting to reach failureThreshold before fallback

[y-rabie]

The change removes a part that used to manually and immediately scale to Fallback.Replicas on encountering an error. Scaling to fallback is already done in GetMetricsWithFallback by recording an appropriate metric value the HPA will use, but only after Fallback.FailureThreshold failures.

The current existence of this part causes Fallback.FailureThreshold to be effectively unused.

doFallbackScaling and setFallbackCondition functions are removed since they are no longer used. The test TestScaleToFallbackReplicasWhenNotActiveAndIsError is no longer applicable I think

Checklist

• When introducing a new scaler, I agree with the scaling governance policy
• I have verified that my change is according to the deprecations & breaking changes policy
• Tests have been added
• Changelog has been updated and is aligned with our changelog requirements
• A PR is opened to update our Helm chart (repo) (if applicable, ie. when deployment manifests are modified)
• A PR is opened to update the documentation on (repo) (if applicable)
• Commits are signed with Developer Certificate of Origin (DCO - learn more)

[JorTurFer]

/run-e2e fallback
Update: You can check the progress here

[y-rabie]

I've pushed a trivial change that should fix the failing test. @JorTurFer if you can re-trigger the e2e tests 😄

[zroubalik]

/run-e2e fallback
Update: You can check the progress here

[JorTurFer]

/run-e2e fallback
Update: You can check the progress here

[JorTurFer]

nice job! Thanks 😄