[Android][Passwords] Enable filling across all origins per default

The feature is launched for a while now.

A lot of the showing logic depended on checking whether there
is a source available that is worth showing. Since filling across
origins is always available (except on search fields and text areas),
this simplifies the visibility logic even for the legacy accessory.

Bug: 1104132
Change-Id: Ia1951012d1990977bb19f80dcee8e633454685a1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3103318


Commit-Queue: Friedrich [CET] <fhorschig@chromium.org>
Reviewed-by: Mohamed Amir Yosef <mamir@chromium.org>
Cr-Commit-Position: refs/heads/main@{#914693}