Adjust the space of header & content of Settings'

"Choose a new screen lock" page for expressive style

Set the description view to View.GONE if its content is empty in
expressive style, so it does not occupy any extra space.

Flag: EXEMPT UI customization

Bug: 406937272

Test: Build different project ABTD ROMs to check Toggle UI
Change-Id: I1ce31e0804922972c9179f17cc4a91e24273cba3