[WIP] Fix BatchNormalization layer export issue in ONNX model

[Copilot]

• Verify final name-fixing behavior and optimizer test conventions
• Add a focused regression test for unnamed optional outputs
• Remove the optimizer step that reassigns cleared output names
• Run targeted tests, lintrunner, secret scan, and security validation

• Fixes BatchNormalization layer with training_mode=1 results in incorrect ONNX model #2969

[justinchuby]

@copilot name fix pass is still needed. Let me know if onnx-ir needs updating or if there is another way to fix it

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 72.64%. Comparing base (457a260) to head (0fc3b8b).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2988   +/-   ##
=======================================
  Coverage   72.63%   72.64%           
=======================================
  Files         265      265           
  Lines       32205    32212    +7     
  Branches     3041     3041           
=======================================
+ Hits        23392    23399    +7     
  Misses       7779     7779           
  Partials     1034     1034           

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