Ambient: Pulse for every noisy notification exactly once

Also increases the pulse duration and switches timing to
elapsed realtime instead of wall time for robustness. Also
remove triggering for notification light for simplifying code.
Only noisy notifications are able to trigger the light anyway and
noisy notifications already trigger ambient on their own.

Change-Id: I4efbe530bb1a60cabaa46c2b04bcd5e12cdef680
Fixes: 31004875