Fix missing method delegations in RunInference wrapper ModelHandlers

[tvalentyn]

• Added some of the newer hooks to all wrapper ModelHandler classes so they forward these hooks to self._base or self._unkeyed.

• Added a meta-test test_wrapper_model_handlers_override_all_model_handler_methods to verify that wrappers override all methods from the base ModelHandler class to prevent similar omissions.

• Fix a copypasting error.

[github-actions]

📋 Review Summary

This PR properly ensures that wrapper ModelHandler classes (KeyedModelHandler, MaybeKeyedModelHandler, _PrebatchedModelHandler, _PreProcessingModelHandler, and _PostProcessingModelHandler) delegate all relevant hooks (update_model_paths, override_metrics, should_skip_batching, and should_garbage_collect_on_timeout) to their inner model handlers. It also fixes a logging format bug in KeyedModelHandler.__init__ and introduces comprehensive unit tests, including a reflection-based meta-test to prevent future delegation omissions.

🔍 General Feedback

• The delegation implementations are clean, consistent across all wrapper classes, and properly handle single-model vs. multi-model cases in KeyedModelHandler.
• Adding test_wrapper_model_handlers_override_all_model_handler_methods is a great safeguard against future drift when new methods are added to the base ModelHandler class.

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[codecov]

Codecov Report

❌ Patch coverage is 96.96970% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 79.92%. Comparing base (76f6e6d) to head (e264527).
⚠️ Report is 178 commits behind head on master.

Files with missing lines	Patch %	Lines
sdks/python/apache_beam/ml/inference/base.py	96.96%	1 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             master   #40602       +/-   ##
=============================================
+ Coverage     56.16%   79.92%   +23.75%     
=============================================
  Files          1124      488      -636     
  Lines        178336    82416    -95920     
  Branches       1489        0     -1489     
=============================================
- Hits         100170    65874    -34296     
+ Misses        75645    16542    -59103     
+ Partials       2521        0     -2521     

Flag	Coverage Δ
go	?
java	?
python	79.92% <96.96%> (+0.37%)	⬆️

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[github-actions]

Assigning reviewers:

R: @shunping for label python.
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[shunping]

LGTM, thanks!