[PermissionsAI] Optimize AIV4 model downloads on Android

This change introduces specific download scheduling parameters for the
Permissions AIv4 model on Android builds.

To optimize resource usage on mobile devices, the model downloads are
now scheduled with the following conditions on Android:
- Priority: NORMAL
- Battery: BATTERY_SENSITIVE
- Network: UNMETERED

For all other platforms, the behavior remains unchanged, using the
default
download parameters.

Bug: 382447738
Change-Id: I111a63e2b33e1189f726cfe135e7035a2433b3f2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7037977
Commit-Queue: Judith Hemp <hempjudith@google.com>
Reviewed-by: Elias Klim <elklm@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1529729}