Add linting for unreachable code

[Affan-7]

What type of PR is this?

/kind cleanup

What this PR does / why we need it:

This PR enables linting for the unreachable code.

Which issue(s) this PR fixes:
Part of #4490

Does this PR introduce a user-facing change?:

NONE

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (bef4e7a) 51.86% compared to head (d85a32f) 51.85%.

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Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4514      +/-   ##
==========================================
- Coverage   51.86%   51.85%   -0.01%     
==========================================
  Files         243      243              
  Lines       24183    24183              
==========================================
- Hits        12543    12541       -2     
- Misses      10959    10961       +2     
  Partials      681      681              

Flag	Coverage Δ
unittests	51.85% <ø> (-0.01%)	⬇️

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[RainbowMango]

Hi @Affan-7 There is a conflict you need to resolve.

[RainbowMango]

/lgtm
/approve

I helped rebase the code.

[karmada-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: RainbowMango

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[Affan-7]

I helped rebase the code.

Thanks!