Move padding from parent to WidgetPagedView and siblings in 2-pane pkr

WidgetPagedView seems to rely on padding to position it such that
 talkback doesn't focus on it before sticky header.

Bug: 348107507
Test: With talkback
Flag: EXEMPT bugfix
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:adc171b3136dda72225ad2930604195a3c13122e)
Merged-In: I2fcdc0cbf027a7a8c1bee104f85a61f700faf776
Change-Id: I2fcdc0cbf027a7a8c1bee104f85a61f700faf776