Adjust Wallet Quick Affordance picker String to use correct resource

We were previously using an accessibility string within the Wallpaper
picker to display the name for the Wallet. We should change this to be
`wallet_title` to align with the qr code scanner's implementation.

Bug: 337014257
Test: manual - observe string change in code
Flag: EXEMPT bugfix
Change-Id: I27e283f2173b38a997b634f5d3f1f4c04e350e33