Do not launch clock when touching the clock on the lockscreen

Bug: 7640566

On the lock screen:
Do not launch clock at all, launch CitiesActivity when clicking on the world clock.
On the home screen:
Launch the clock app when touching the clock, launch CitiesActivity when
clicking on the world clock.

Change-Id: I09302f35c7c585bfd1db010eb3f14feea84e34af