Checkfallbackvalid

[ctccxxd]

Revise some annotations and fix fallback check, originally,
1, Annotations above function is not well
2, Fallback check does not take effect
3, validate the case fallback with cpu/memory

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)

related issue
#6355

[ctccxxd]

Friendly ping @wozniakjan @JorTurFer I have follow your idea to validate the case fallback with cpu/memory, hope your review, much thanks.