feat: strategytype should be duplicated, add default case for Replica…

[vie-serendipity]

…DivisionPreference

What type of PR is this?

/kind feature

What this PR does / why we need it:
According to this snippet of code, default ReplicaSchedulingType should be Duplicated.

func (p *Placement) ReplicaSchedulingType() ReplicaSchedulingType {
	if p.ReplicaScheduling == nil {
		return ReplicaSchedulingTypeDuplicated
	}

	return p.ReplicaScheduling.ReplicaSchedulingType
}

And in case that ReplicaSchedulingType is divided and ReplicaDivisionPreference is not defined, default ReplicaDivisionPreference should be added. I think Aggregated is more appropriate.
Which issue(s) this PR fixes:
Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

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Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 28.23%. Comparing base (1432eca) to head (4ea4f6e).

Files	Patch %	Lines
pkg/scheduler/core/assignment.go	0.00%	2 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5289      +/-   ##
==========================================
+ Coverage   28.22%   28.23%   +0.01%     
==========================================
  Files         632      632              
  Lines       43762    43764       +2     
==========================================
+ Hits        12350    12355       +5     
+ Misses      30508    30507       -1     
+ Partials      904      902       -2     

Flag	Coverage Δ
unittests	28.23% <0.00%> (+0.01%)	⬆️

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[XiShanYongYe-Chang]

Hi @vie-serendipity thanks for your contribution!
/assign

[whitewindmills]

And in case that ReplicaSchedulingType is divided and ReplicaDivisionPreference is not defined, default ReplicaDivisionPreference should be added. I think Aggregated is more appropriate.

now its default value is Weighted, why do you need to change its default value?

[XiShanYongYe-Chang]

Hi @vie-serendipity, when .spec.placement.replicaScheduling is empty, the ReplicaSchedulingType will be regarded as Duplicated, otherwise it will be regarded as Diveded, related discussion can refer here: #3014

[vie-serendipity]

@XiShanYongYe-Chang Thanks, the discussion was clear, I got it.

[vie-serendipity]

@whitewindmills At first I didn't see a default weight reference, now I think weighted makes sense.

[vie-serendipity]

Thanks for your time.

[XiShanYongYe-Chang]

@vie-serendipity Still thank you for your enthusiasm and participation in the community. Looking forward to your continued contribution. ^-^

By the way, are you using Karmada, or are you learning Karmada?

[vie-serendipity]

I'm still learning Karmada, I think it's an awesome project.

[XiShanYongYe-Chang]

Thanks @vie-serendipity