Revert "Add version for DownloadRestrictions on iOS"

This reverts commit ad1d13c344aed9b8c752681c5abfa713ccc91626.

Reason for revert: Policy is not available yet as testing is not done

Original change's description:
> Add version for DownloadRestrictions on iOS
>
> Bug: 349803637
> Change-Id: Iae9026540bd85e4104850850b15b1fec27a0dbc0
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6207970
> Reviewed-by: Alexander Hendrich <hendrich@chromium.org>
> Commit-Queue: Alexander Hendrich <hendrich@chromium.org>
> Reviewed-by: Cheick Cisse <cheickcisse@google.com>
> Auto-Submit: Dominique Fauteux-Chapleau <domfc@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1413419}

BYPASS_POLICY_COMPATIBILITY_CHECK="Revert needed for untested policy in M134"

Bug: 349803637
Change-Id: I698ed5f5bc2435f67bca355f693ee680f78ed84b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6253064
Reviewed-by: Dominique Fauteux-Chapleau <domfc@chromium.org>
Reviewed-by: Alexander Hendrich <hendrich@chromium.org>
Commit-Queue: Ernesto Izquierdo Clua <eic@google.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Reviewed-by: Cheick Cisse <cheickcisse@google.com>
Cr-Commit-Position: refs/heads/main@{#1419872}