Revert "[Perf] fuse more rmsnorm and all-reduce in qwen3.5" (#46998)

[vllm-agent]

Revert of #46998

This reverts the merge commit 300e337 from PR #46998.

Reason: This PR is linked to 1 new CI failure in build #77569:

• Fusion E2E TP2 Quick (H100) — test_tp2_ar_rms assertions fail expecting fusion counts that no longer match after rmsnorm fusion changes

The test_tp2_ar_rms_fp8_fusions and test_tp2_ar_rms_fusions tests fail with:

• AssertionError: Expecting full rms+quant fusion where ar+rms+quant not activated
• AssertionError: Could not find 2 ar_rms_fusion (found 0)

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[mergify]

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

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