Pausing an expired timer should reset it

Bug: 22371346

This is a use case that can only occur via system intents and not
via the user interface. Since the utility of pausing and/or resuming
an expired timer is dubious at best, the effect is now changed to
reset the expired timer.

Change-Id: I28c7500d1393dcfade1303b31de750c525dd0df3