[Hardware][AMD][CI] Fix Kernels Attention test groups

[mawong-amd]

Purpose

This PR fixes both the gfx942 and gfx950-based Kernels Attention test groups.

The following 3 test groups are now newly passing in AMD CI:
MI300_1: Kernels Attention %N
MI355_1: Kernels Attention %N
MI355_1: Kernels (B200-MI355)

Test Plan

pytest -sv tests/kernels/attention on both gfx942 and gfx950-based machines.

Test Result

The test groups pass. They are run as part of AMD CI here.

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Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.

[tjtanaa]

LGTM, will come back and check the AMD CI status.

Kernels Attention Test %N (mi300)
Kernels Attention Test %N (mi355)
Kernels (B200-MI355)

[mawong-amd]

Added the remaining fixes needed for MI355_1: Kernels Attention %N and MI355_1: Kernels (B200-MI355) to pass (previously was limited to just MI300_1: Kernels Attention %N) and triggered the relevant test groups.

[mergify]

Hi @mawong-amd, the pre-commit checks have failed. Please run:

uv pip install pre-commit>=4.5.1
pre-commit install
pre-commit run --all-files

Then, commit the changes and push to your branch.

For future commits, pre-commit will run automatically on changed files before each commit.

[tjtanaa]

@mawong-amd can you sync with main again. It seems the error is gone in latest nightly https://buildkite.com/vllm/ci/builds/72616/list

[mawong-amd]

The remaining error in H100 batch invariance appears unrelated to this PR

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @mawong-amd.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

[mawong-amd]

Closing in favor of #46080 because this PR has merge conflicts which can no longer be resolved, since the source branch is no longer writeable.