Revert "Mark some additional node-related classes as main thread only."

This reverts commit 44eb83eedd82f46ecaa3c4f9bf7584ed41f485ec.

Reason for revert: Suspected root cause for b/395051478

Original change's description:
> Mark some additional node-related classes as main thread only.
>
> This appears to be about 0.1% improvement on Speedometer3.
>
> Bug: 392929914
> Change-Id: Id7c524b1f0066421c20982a59015cf7b7ced16c8
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6208988
> Reviewed-by: Ian Kilpatrick <ikilpatrick@chromium.org>
> Commit-Queue: David Baron <dbaron@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1412602}

Bug: 392929914, 395051478
Change-Id: I68c032d596db6b0b819c86b063c7094d75e03411
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6278365
Auto-Submit: Benoit Lize <lizeb@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Benoit Lize <lizeb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1421826}