Keep creating constants when constants are folded inside ir.Function

[titaiwangms]

Fixes #2673

[codecov]

Codecov Report

❌ Patch coverage is 78.04878% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 70.11%. Comparing base (1a27df1) to head (1c7fc2c).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
onnxscript/optimizer/_constant_folding.py	73.52%	3 Missing and 6 partials ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2679   +/-   ##
=======================================
  Coverage   70.11%   70.11%           
=======================================
  Files         224      224           
  Lines       26956    26982   +26     
  Branches     2700     2705    +5     
=======================================
+ Hits        18899    18919   +20     
- Misses       7126     7129    +3     
- Partials      931      934    +3     

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[justinchuby]

Thanks - minor comments. Would be good to get another eye from @gramalingam