🧪 [MockingTemplateLoader] Add test for TemplateAlreadyDefinedException

[RoiSoleil]

🎯 What: Added missing test to MockingTemplateLoaderTest.java to cover the path where TemplateAlreadyDefinedException is caught and added to the invalid templates results.
📊 Coverage: MockingTemplateLoader.java line 69 is now tested.
✨ Result: Improved test coverage for MockingTemplateLoader error path.

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PR created automatically by Jules for task 8253897027526835219 started by @RoiSoleil

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.40%. Comparing base (056906c) to head (12cb502).
⚠️ Report is 11 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #253      +/-   ##
============================================
+ Coverage     73.28%   73.40%   +0.12%     
- Complexity     3234     3242       +8     
============================================
  Files           420      421       +1     
  Lines         14435    14479      +44     
  Branches       1266     1267       +1     
============================================
+ Hits          10578    10628      +50     
+ Misses         3325     3317       -8     
- Partials        532      534       +2     

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