Revert "Remove fuchsia from policy yaml definition - Part I"

This reverts commit b20cbcc9edd27038f5f73dad22b1206d9a51b907.

Reason for revert: likely causing tree closure
https://ci.chromium.org/ui/p/chromium/builders/try/fuchsia-x64-cast-receiver-rel/771262/blamelist

Original change's description:
> Remove fuchsia from policy yaml definition - Part I
>
> Massive remove fuchsia platforms from policy files as we are not going
> to support them.
>
> Bug: 367623932
> Change-Id: I0b7a48d63fb818335b5fcdcfecafe03f01d63d0f
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5867084
> Reviewed-by: Yann Dago <ydago@chromium.org>
> Commit-Queue: Yann Dago <ydago@chromium.org>
> Auto-Submit: Owen Min <zmin@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1356670}

Bug: 367623932
Change-Id: Ie47a6a8d583041a443968e9a4914223f1e165eba
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5870784
Auto-Submit: Nicolás Peña <npm@chromium.org>
Owners-Override: Nicolás Peña <npm@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1356703}