[media-preview] Update camera/mic permission requests string (UXW spec)

Bug: b:345570403
Change-Id: I8c41dbad5d69a390b5cd2bd2a16f327c69ddf651
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5561963


Reviewed-by: Ken Rockot <rockot@google.com>
Commit-Queue: Ahmed Moussa <ahmedmoussa@google.com>
Reviewed-by: Balazs Engedy <engedy@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1313073}