Remove unused function before version converter

[titaiwangms]

In old torch versions, until 2.9, the converted models include unused Rank onnx function which blocks version converter to function.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 70.40%. Comparing base (bfee593) to head (80272d9).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2816   +/-   ##
=======================================
  Coverage   70.40%   70.40%           
=======================================
  Files         228      228           
  Lines       27140    27140           
  Branches     2727     2727           
=======================================
  Hits        19108    19108           
  Misses       7096     7096           
  Partials      936      936           

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