Revert "Move {ash => chromeos/ash}/components/policy/"

This reverts commit a61cd5af5a75743c52efb274cdbe93bd9cf96d04.

Reason for revert: Tree closing

Original change's description:
> Move {ash => chromeos/ash}/components/policy/
>
> ChromeOS components and services are meant to live in chromeos/,
> separate from Ash shell code. Fix a previous migration that used the
> wrong directory.
>
> This CL is part of the ChromeOS source code directory migration:
> https://docs.google.com/document/d/1g-98HpzA8XcoGBWUv1gQNr4rbnD5yfvbtYZyPDDbkaE.
>
> Bug: 1164001
> Change-Id: I0d8cdd2fa221f89befcb169b8de27c56da9e4390
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3867647
> Reviewed-by: James Cook <jamescook@chromium.org>
> Owners-Override: James Cook <jamescook@chromium.org>
> Commit-Queue: Henrique Ferreiro <hferreiro@igalia.com>
> Cr-Commit-Position: refs/heads/main@{#1052671}

Bug: 1164001
Change-Id: I9764aa425dbb1437d4b4e55c09bb1819aa46cbbd
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3925053
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Anthony Cui <cuianthony@chromium.org>
Owners-Override: Anthony Cui <cuianthony@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1052683}