Fix ScreenDecorations user switch bug

If a configuration change occurs right after creating a new user,
ScreenDecorations could try to get the SecureSetting for a user that
hasn't been set up yet. Instead, rely on the broadcast receiver to
receive the USER_SWITCH broadcast to update the SecureSetting for color
inversion.

Test: manual
Fixes: 152725163
Change-Id: I9d0b454b1b5d87d09a8bf995c283e435028fe2c6