Fix MatMulScaleFusion handling of scales with leading dimensions. (#24492)
### Description
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Fix MatMulScaleFusion handling of scales with leading dimensions. The
previous approach accepted a Mul/Div with a scale that broadcasted
additional leading dimensions to its output shape. This caused a shape
mismatch in the fused replacement.
### Motivation and Context
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- If it fixes an open issue, please link to the issue here. -->
Fix #24407.