Added tests for federatedhpa controller

[anujagrawal699]

Description:
This PR introduces the first set of comprehensive unit tests for the Federated Horizontal Pod Autoscaler (FederatedHPA) controller and its associated components. Due to the extensive nature of the test additions, i'll try to split the test additions into 2 PR's.

Additions:

1. FederatedHPA Controller (pkg/controllers/federatedhpa/federatedhpa_controller_test.go)
2. Metrics Client (pkg/controllers/federatedhpa/metrics/client_test.go)
3. Replica Calculator (pkg/controllers/federatedhpa/replica_calculator_test.go)
4. Config Types (pkg/controllers/federatedhpa/config/types_test.go)

Test Coverage Improvements:
federatedhpa_controller_test.go: 0% to 41.2% (More tests will be added in the future PR)
client_test.go: 0% to 92.9%
replica_calculator_test.go: 0% to 85.7%
types_test.go: 0% t 100%

What type of PR is this?
/kind documentation
/kind failing-test
/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 33.70%. Comparing base (4ac95b9) to head (337f787).

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Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5528      +/-   ##
==========================================
+ Coverage   32.45%   33.70%   +1.25%     
==========================================
  Files         643      643              
  Lines       44497    44497              
==========================================
+ Hits        14440    14999     +559     
+ Misses      28962    28355     -607     
- Partials     1095     1143      +48     

Flag	Coverage Δ
unittests	33.70% <ø> (+1.25%)	⬆️

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[anujagrawal699]

@XiShanYongYe-Chang Could you please trigger a retest?

[XiShanYongYe-Chang]

You can enter this amount command
/retest

[XiShanYongYe-Chang]

Nice job!
/lgtm
/approve

[karmada-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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[XiShanYongYe-Chang]

/remove-kind documentation

[anujagrawal699]

@XiShanYongYe-Chang Do a test file for pkg/controllers/federatedhpa/monitor/metrics.go and pkg/controllers/federatedhpa/monitor/monitor.go needed?

[XiShanYongYe-Chang]

You can try it. I'll see how it works.