Change MAP to send one new message event upon storage unlock

The MAP service will now send one new message event for all messages
when device storage is unlocked instead of sending an event per message.

Bug: 30809925
Change-Id: I1c9e10125c9a754bf4f6c25718fc0422d79cf37e
(cherry picked from commit 8b02ffef2611c8f21d751e5a196bcb765a9e997e)
(cherry picked from commit ac3a80eed68e2374151abb59e66d95bb2e66cf61)