Remove managed label in collected endpointslice and derived service

[XiShanYongYe-Chang]

What type of PR is this?

/kind cleanup

What this PR does / why we need it:

As comment in #4620 (comment), we do not need to add the karmada.io/managed label to the collected endpointslice and derived service, so I removed it.

Which issue(s) this PR fixes:
Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

[XiShanYongYe-Chang]

Hi @a7i , can you help take a look?
/cc @a7i

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 28.20%. Comparing base (c8acebc) to head (9aee020).

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Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5147      +/-   ##
==========================================
- Coverage   28.21%   28.20%   -0.01%     
==========================================
  Files         632      632              
  Lines       43568    43564       -4     
==========================================
- Hits        12291    12289       -2     
+ Misses      30381    30378       -3     
- Partials      896      897       +1     

Flag	Coverage Δ
unittests	28.20% <ø> (-0.01%)	⬇️

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[a7i]

/lgtm

[RainbowMango]

/approve

[karmada-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: a7i, RainbowMango

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