disable sdpa in static attention mha forward

[billmguo]

Differential Revision: D87944616

[pytorch-bot]

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❌ 1 New Failure, 1 Cancelled Job, 1 Unrelated Failure

As of commit 06fd912 with merge base 18c1c5b ():

NEW FAILURE - The following job has failed:

• Lint / lintrunner / linux-job (gh)
  >>> Lint for examples/apple/coreml/llama/utils.py:

CANCELLED JOB - The following job was cancelled. Please retry:

• Check Labels (gh)

BROKEN TRUNK - The following job failed but were present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• pull / android / run-emulator (gh) (trunk failure)
  Timeout waiting for emulator to boot.

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[meta-codesync]

@billmguo has exported this pull request. If you are a Meta employee, you can view the originating Diff in D87944616.

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[metascroy]

@billmguo are the changes in llama_transformer.py identical to the ones here #16057 (except this PR doesn't implement the 3-part split)?