Fall back to default custom shortcuts if custom shortcuts are disabled

Bug: b/281528589
Test: manual - customize shortcuts, disable customization, then observe falling back to defaults
Change-Id: I6d74cf9960a09b7d3261154e711f824058b0d25a
Merged-In: I6d74cf9960a09b7d3261154e711f824058b0d25a
5 files changed