control/zone: Refactor addTimer

Anything adding a timer uses roughly the same process of building the
event data and timer from the event group, actions, and timer config. We
can adjust the method to do this for all callers.

Tested:
    Builds and passes unit tests.

Change-Id: I4013ff2f7bff65095a6e1db7075bc013da374f51
Signed-off-by: William A. Kennington III <wak@google.com>
3 files changed