Revert "[Settingslib] Fixed Preference background"

Revert submission 31966577-bg-fix

Bug: b/399727309

Reason for revert: Broke the Settings app layout, see b/399727309 | [BP2A][ZP1A][All devices] Clustering in Settings has mostly gone away

Note that there is a fix forward in progress, so we will not submit this revert (unless there is a delay in getting the fix forward) but we do want to be able to cherry-pick this into the next daily build while waiting for the revert.

Reverted changes: /q/submissionid:31966577-bg-fix
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:f6ab176ec726786a75293c9ebea2161592c13c17)
Merged-In: I4c4836e163e85abb09280f6ce96db5f1c24fbc28
Change-Id: I4c4836e163e85abb09280f6ce96db5f1c24fbc28