Fix message list backgrounds in wide mode.

The final asset drop renamed things to conversation_wide and I had
missed this case for the unread states (the rename went fine for the
read case). As a result, we didn't actually import the new unread states
for wide mode.

Bug: 5286632
Change-Id: I5b1f4120ce42ff50d713706c319260ff57274648
21 files changed