feat: add average replicas assign proposal

[ipsum-0320]

What type of PR is this?

/kind feature /kind documentation

What this PR does / why we need it:

Which issue(s) this PR fixes: Fixes part of #5159

Special notes for your reviewer: @whitewindmills

Does this PR introduce a user-facing change?:

NONE

Other related issues: #4085

[whitewindmills]

/retest

[codecov-commenter]

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Codecov Report

Attention: Patch coverage is 98.24561% with 1 line in your changes missing coverage. Please review.

Project coverage is 34.22%. Comparing base (ef7d528) to head (68134e6).

Files with missing lines	Patch %	Lines
.../scheduler/core/spreadconstraint/group_clusters.go	98.24%	1 Missing :warning:

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #5225 +/- ## ========================================== + Coverage 34.15% 34.22% +0.06% ========================================== Files 643 643 Lines 44503 44551 +48 ========================================== + Hits 15201 15248 +47 - Misses 28145 28146 +1 Partials 1157 1157 ``` | [Flag](https://app.codecov.io/gh/karmada-io/karmada/pull/5225/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=karmada-io) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/karmada-io/karmada/pull/5225/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=karmada-io) | `34.22% <98.24%> (+0.06%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=karmada-io#carryforward-flags-in-the-pull-request-comment) to find out more.

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[whitewindmills]

invite these people to help with the review. /cc @RainbowMango @XiShanYongYe-Chang @chaunceyjiang @chaosi-zju @zhzhuang-zju

[ipsum-0320]

@whitewindmills yeah, thanks, I have received your comments and will make some changes.

[ipsum-0320]

/retest

[karmada-bot]

@ipsum-0320: Cannot trigger testing until a trusted user reviews the PR and leaves an /ok-to-test message.

In response to [this](https://github.com/karmada-io/karmada/pull/5225#issuecomment-2238695496): >/retest > Instructions for interacting with me using PR comments are available [here](https://git.k8s.io/community/contributors/guide/pull-requests.md). If you have questions or suggestions related to my behavior, please file an issue against the [kubernetes-sigs/prow](https://github.com/kubernetes-sigs/prow/issues/new?title=Prow%20issue:) repository.

[ipsum-0320]

i have update the proposal, everyone is welcome to give me some feedback. /cc @whitewindmills @warjiang @RainbowMango @XiShanYongYe-Chang @chaunceyjiang @chaosi-zju @zhzhuang-zju

[ipsum-0320]

/retest

[karmada-bot]

@ipsum-0320: Cannot trigger testing until a trusted user reviews the PR and leaves an /ok-to-test message.

In response to [this](https://github.com/karmada-io/karmada/pull/5225#issuecomment-2258315725): >/retest Instructions for interacting with me using PR comments are available [here](https://git.k8s.io/community/contributors/guide/pull-requests.md). If you have questions or suggestions related to my behavior, please file an issue against the [kubernetes-sigs/prow](https://github.com/kubernetes-sigs/prow/issues/new?title=Prow%20issue:) repository.

[whitewindmills]

/ok-to-test

[ipsum-0320]

/retest

[whitewindmills]

@RainbowMango @chaunceyjiang @warjiang still need your review. do you have any comment?

[whitewindmills]

ping @RainbowMango @chaunceyjiang @warjiang @XiShanYongYe-Chang

[ipsum-0320]

@RainbowMango @chaunceyjiang @warjiang @XiShanYongYe-Chang Does anyone have any questions? 😁

[XiShanYongYe-Chang]

LGTM

We are about to release a major version (v1.11) soon (by the end of this month), and it seems that this feature will not make it into this version. We can start to quickly advance this feature in early September.

[chaunceyjiang]

/assign

[XiShanYongYe-Chang]

Hi @RainbowMango @whitewindmills @chaunceyjiang can we get on with this mission?

[whitewindmills]

I'm ok with it, and seems that it looks good to @XiShanYongYe-Chang. ping @RainbowMango @chaunceyjiang

[RainbowMango]

I'll look at it today.

[karmada-bot]

Adding label do-not-merge/contains-merge-commits because PR contains merge commits, which are not allowed in this repository. Use git rebase to reapply your commits on top of the target branch. Detailed instructions for doing so can be found here.

Instructions for interacting with me using PR comments are available [here](https://git.k8s.io/community/contributors/guide/pull-requests.md). If you have questions or suggestions related to my behavior, please file an issue against the [kubernetes-sigs/prow](https://github.com/kubernetes-sigs/prow/issues/new?title=Prow%20issue:) repository.

[karmada-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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