Remove spurious syncmanager wake-ups

BUG: 22287469
1) Fix SyncManager waking up every 2 hrs if there is nothing
to do.
2) Fix sync wake-up alarm not being properly updated if the new
alarm was in the future.
2a) Due to staus bar sync signal that were removed post-K
one of the wake-ups was for 30s in the future, removed this
@hide intent completely.
3) The SyncManager will still set a timeout alarm for 5mins after
the start of a sync. Leaving this in as to post to a handler is
less expensive but more complex, and the alarm update is
correctly working now.

Change-Id: If51c9dd68391ccaeb480a17eb5a1364c4afe4c2a