fix: optimize all checkRepliacas code and fix the problem does not take effect

[ctccxxd]

fix and optimize all checkReplicas code, originally 1, Webhook for replicas check does not take effect. 2, No check for negative value. 3, Variable max or min is same with build-in function name, not graceful 4, Have no defaultMaxReplicas for hpa. 5, Code has redundency.

Checklist

• [ ] When introducing a new scaler, I agree with the scaling governance policy
• [x] I have verified that my change is according to the deprecations & breaking changes policy
• [ ] Tests have been added
• [x] 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)
• [x] Commits are signed with Developer Certificate of Origin (DCO - learn more)

related issue https://github.com/kedacore/keda/issues/6356

[ctccxxd]

Friendly ping @zroubalik @wozniakjan @SpiritZhou @psi @wonko @fivesheep @JorTurFer hope you to review and discuss, much thanks.

[ctccxxd]

I think that I'm missing something. Can't we just include the negative check message in the current GetHPAMin/MaxReplicas funcs and it'd do almost the same, wouldn't?

Much thanks for your comments. Originally. it has much logic in GetHPAMin/MaxReplicas funcs including default replicas logic. I hink it is not very explicit for user to read. I want to make the logic more clean. Besides, I have more purposes,

1, Webhook for replicas check does not take effect. 2, No check for negative value. 3, Variable max or min is same with build-in function name, not graceful 4, Have no defaultMaxReplicas for hpa. 5, Code has redundency. Hope for your reply.