Added tests for pkg/detector

[anujagrawal699]

Description:
This PR enhances the unit tests for the Resource Detector in the detector package. The improvements aim to increase code reliability, maintainability, and test coverage for the Resource Detector.
This PR introduces comprehensive unit tests for various functions in the Resource Detector, including:

• GVRDisabled and NeedLeaderElection
• EventFilter
• OnAdd, OnUpdate, OnDelete
• LookForMatchedPolicy and LookForMatchedClusterPolicy
• ApplyPolicy and ApplyClusterPolicy
• ClaimPolicyForObject and ClaimClusterPolicyForObject
• BuildResourceBinding and BuildClusterResourceBinding
• isWaiting, AddWaiting and RemoveWaiting
• Handling of PropagationPolicy and ClusterPropagationPolicy events
• Cleanup operations for ResourceBinding and ClusterResourceBinding

Additions and Modifications:

1. pkg/detector/detector_test.go

Test Coverage:

1. detector_test.go: Significant increase in coverage from 1.62% to 50.80%

Overall coverage of detector package: 19.58% to 50.00%

What type of PR is this?
/kind feature

Which issue(s) this PR fixes:
Fixes a part of #5470

Does this PR introduce a user-facing change?:

NONE

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 35.92%. Comparing base (8cc712f) to head (2d343b6).

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Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5631      +/-   ##
==========================================
+ Coverage   35.19%   35.92%   +0.73%     
==========================================
  Files         645      645              
  Lines       44869    44869              
==========================================
+ Hits        15791    16121     +330     
+ Misses      27846    27448     -398     
- Partials     1232     1300      +68     

Flag	Coverage Δ
unittests	35.92% <ø> (+0.73%)	⬆️

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[XiShanYongYe-Chang]

Hi @anujagrawal699 How about splitting this pr?

[XiShanYongYe-Chang]

/assign

[anujagrawal699]

Tracked by #5711 and #5746