This reverts commit e13a744a.

Reason for revert: breaks perfetto:
https://ci.chromium.org/p/v8/builders/ci/V8%20Linux64%20-%20debug%20-%20perfetto%20-%20builder/12849

Original change's description:
> [build] Fix gn check failures in v8/third_party
>
> This removes the blanket exclusion for third_party but leaves
> third_party/icu excluded (which is the same as chrome).
>
> Most fixed issues are to do with previously removed header files and
> missing dependencies.
>
> Bug: v8:7330
> Change-Id: I7e634e35c0620a1f3db9aba01119921e4f781e3e
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2856838
> Auto-Submit: Dan Elphick <delphick@chromium.org>
> Reviewed-by: Michael Achenbach <machenbach@chromium.org>
> Commit-Queue: Michael Achenbach <machenbach@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#74295}

Bug: v8:7330
Change-Id: I05cf897c0aeb6bf87f9889b878358c0d02600081
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2862767
Auto-Submit: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#74300}