[js/webgpu] Fix attention shader recompilation issue (#21770)
### Description
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This PR fixes the `AttentionProbsSoftmax` recompilation issue when
executing the phi3 model. With this fix, it will further improve the
phi3 performance.
### Motivation and Context
<!-- - Why is this change required? What problem does it solve?
- If it fixes an open issue, please link to the issue here. -->