[dlc-predownload-list] Update DeviceDlcPredownloadList item caption

Update DeviceDlcPredownloadList item caption so that it's the same as
text on the Dpanel settings page (see changes in cl/619913540).

I'm not sure if I should change the name and the value of this policy.
"value" is only used for internal representation and "name" is not
used at all(?), so I think it's OK to keep them as is.

Bug: b/331608413
Change-Id: I8d002518111cba387ef1c994b39a0925d8e51f6e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5413513


Reviewed-by: Yann Dago <ydago@chromium.org>
Auto-Submit: Andrei Nedoluzhko <nedol@google.com>
Commit-Queue: Andrei Nedoluzhko <nedol@google.com>
Reviewed-by: Sparik Hayrapetyan <ust@google.com>
Cr-Commit-Position: refs/heads/main@{#1282368}