Increase DEFAULT_CONSTANT_FOLD_INPUT_SIZE_LIMIT (#2527)

I have seen graphs like `Add(bias, 1)` in gemma3 where bias is an
initializer. (Why?) This PR increases the default input limit so these
bias initializers can be folded

Author: justinchuby

onnxscript/optimizer/_constant_folding.py

@@ -19,7 +19,7 @@
 import onnxscript.utils.utils as utils
 from onnxscript.ir import _tape
 
-DEFAULT_CONSTANT_FOLD_INPUT_SIZE_LIMIT = 512
+DEFAULT_CONSTANT_FOLD_INPUT_SIZE_LIMIT = 8192
 
 DEFAULT_CONSTANT_FOLD_OUTPUT_SIZE_LIMIT = 512 * 512