autofill save: do not focus on custom sub title for TV

Custom sub title is put in a ScrollView, which steals the
initial focus from Yes/No button when lauching save dialog.

The ScrollView is focusable so it can scroll large views.
But it's quite useless at this point because layout use
"wrap_content" in height, unless the custom subtitle is
higher than fullscreen, we never uses the ScrollView's scroll
feature.

The problem for using ScrollView is:
- TV UX does not allow custom sub title to be focusable or
  scrollable.
- If changes TV UX to allow scrollable custom title view,
  focus indicator of ScrollView is missing, needs to be fixed.

Based on these reasons, disable scrollable feature for TV.

Bug: 79591730
Test: manually tested on AndroidTV
Change-Id: Ib6022daf822b8b977e9a2d4a831a8ba714fb321c