OnnxStaticQuantization: Remove quant_preprocess=False default for qnn ep

[jambayk]

Describe your changes

quant_preprocess was originally set to False by default because I thought it might not be compatible with QNN EP. However, it is needed for most models for the quantization to work properly:

• The quantizer needs a shape inferred model to quantize some tensors.
• Model quality is bad if constants are not made into initializers (see [FR]: prepare_qnn_config should not overwrite op_types_to_quantize if explicitly set #1552).

Checklist before requesting a review

• Add unit tests for this change.
• Make sure all tests can pass.
• Update documents if necessary.
• Lint and apply fixes to your code by running lintrunner -a
• Is this a user-facing change? If yes, give a description of this change to be included in the release notes.
• Is this PR including examples changes? If yes, please remember to update example documentation in a follow-up PR.

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