Align federated StatefulSet's observedGeneration semantics with its native

[liangyuanpeng]

What type of PR is this?

What this PR does / why we need it:
/kind feature

Which issue(s) this PR fixes:
part of #4870

/cc @yike21 @XiShanYongYe-Chang

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

`karmada-controller-manager`: Mark `.status.observedGeneration` of StatefulSet with `.metadata.generation` only when all members' statuses are algined with its resource template generation.

[liangyuanpeng]

Just for reduce unnecessary code of else, happy to have different opinions

[XiShanYongYe-Chang]

I think it's okay~

[codecov-commenter]

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Codecov Report

Attention: Patch coverage is 44.11765% with 19 lines in your changes missing coverage. Please review.

Project coverage is 28.25%. Comparing base (d4c5890) to head (0de6b28).

Files	Patch %	Lines
...esourceinterpreter/default/native/reflectstatus.go	0.00%	18 Missing ⚠️
...ourceinterpreter/default/native/aggregatestatus.go	93.75%	0 Missing and 1 partial ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5204      +/-   ##
==========================================
+ Coverage   28.23%   28.25%   +0.01%     
==========================================
  Files         632      632              
  Lines       43712    43728      +16     
==========================================
+ Hits        12343    12354      +11     
- Misses      30467    30474       +7     
+ Partials      902      900       -2     

Flag	Coverage Δ
unittests	28.25% <44.11%> (+0.01%)	⬆️

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[XiShanYongYe-Chang]

Thanks a lot
/lgtm
/assign @yike21

[yike21]

Thanks!
LGTM

[XiShanYongYe-Chang]

Thanks @yike21
/approve

[karmada-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: XiShanYongYe-Chang

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