fix qdq utils issues and remove global cast replacements

[nvluxiaoz]

What does this PR do?

Type of change: Bug fix

Overview: While attempting to transformers, onnx, torch and modelopt, it is shown the following:

• Original Reshape - Cast - Transpose becomes Reshape - Transpose, so there is no required Cast for int4
• Global cast replacement to FP16 is not required since it will affect other Modules

Usage

# Add a code snippet demonstrating how to use this

Testing

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• Is this change backward compatible?: Yes
• Did you write any new necessary tests?: No
• Did you add or update any necessary documentation?: No
• Did you update Changelog?: No

Additional Information

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[codecov]

Codecov Report

❌ Patch coverage is 90.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 74.31%. Comparing base (ed58324) to head (a51b00d).

Files with missing lines	Patch %	Lines
modelopt/onnx/quantization/qdq_utils.py	90.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #489      +/-   ##
==========================================
+ Coverage   73.46%   74.31%   +0.84%     
==========================================
  Files         180      180              
  Lines       18141    18129      -12     
==========================================
+ Hits        13328    13473     +145     
+ Misses       4813     4656     -157     

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[nvluxiaoz]

@ajrasane Do you know if this pipeline is counted as successful, and if not, what fails? Thanks!