Added tests for metrics and framework package of pkg/scheduler

[anujagrawal699]

Description:
This PR introduces unit tests for the metrics, interface and types in the scheduler package. The improvements aim to increase code reliability, maintainability, and test coverage of the scheduler.

Additions:

1. pkg/scheduler/framework/interface_test.go
2. pkg/scheduler/framework/types_test.go
3. pkg/scheduler/metrics/metrics_test.go

Test Coverage:

1. pkg/scheduler/framework/interface_test.go : 100%
2. pkg/scheduler/framework/types_test.go : 100%
3. pkg/scheduler/metrics/metrics_test.go : 100%

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

[karmada-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 35.31%. Comparing base (6b18b6e) to head (39d3ef3).
Report is 2 commits behind head on master.

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Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5644      +/-   ##
==========================================
+ Coverage   35.19%   35.31%   +0.12%     
==========================================
  Files         645      645              
  Lines       44869    44885      +16     
==========================================
+ Hits        15792    15853      +61     
+ Misses      27846    27800      -46     
- Partials     1231     1232       +1     

Flag	Coverage Δ
unittests	35.31% <ø> (+0.12%)	⬆️

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