Add unit tests for configuration utility

[GautamBytes]

This pull request introduces comprehensive unit tests for the configuration utility functions in pkg/util/configuration/configuration.go.

Changes:

• Adds test cases for the GetTrafficRoutingIngressLuaScript and getRolloutConfiguration functions.
• Uses the fake client from controller-runtime to mock Kubernetes API interactions, ensuring tests are isolated and reliable.
• Covers the following scenarios:
  • Successful retrieval of configuration data and Lua scripts.
  • Graceful handling of non-existent ConfigMap.
  • Correct behavior when a specific key is not found in the ConfigMap.

[kruise-bot]

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[GautamBytes]

@hantmac please review it whenever feasible!

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 47.59%. Comparing base (00aae12) to head (d44d5c0).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #288      +/-   ##
==========================================
+ Coverage   47.52%   47.59%   +0.07%     
==========================================
  Files          63       64       +1     
  Lines        9799     9820      +21     
==========================================
+ Hits         4657     4674      +17     
- Misses       4585     4587       +2     
- Partials      557      559       +2     

Flag	Coverage Δ
unittests	47.59% <ø> (+0.07%)	⬆️

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[GautamBytes]

@furykerry can u rerun the workflow once , it will pass then I just updated branch!