Revert "Disable RendererAllocatesImages on Mac"

This reverts commit c3b3e8cd49b0fef5c0efc5297a925139fa046b0a.

Reason for revert: The bug was fixed in https://crrev.com/c/5331832 so
reenable the feature for M124 rollout.

Original change's description:
> Disable RendererAllocatesImages on Mac
>
> It is causing issues with some widevine videos being on top of the
> primary plane and covering up other content.
>
> Bug: 326802951
> Change-Id: I4fd6fea4ab64036c191fd8092b5768ea0ce72349
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5332973
> Reviewed-by: Xiaohan Wang <xhwang@chromium.org>
> Commit-Queue: Kyle Charbonneau <kylechar@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1266611}

Bug: 40224327
Change-Id: Ic614750a73178bc6c9a057813ef75ceb56bdb1b2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5352140
Commit-Queue: Kyle Charbonneau <kylechar@chromium.org>
Reviewed-by: Kevin Haslett <khaslett@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1270459}