init: shutdown services in the opposite order that they started

Currently, the order that we kill to services during shutdown is the
order of services_ in ServiceManager and that is defacto the order in
which they were parsed, which is not a very useful ordering.

Related to this, we have seen a few issues during shutdown that may be
related to services with dependencies on other services, where the
dependency is killed first and the dependent service then misbehaves.

This change allows services to keep track of the order in which they
were started and shutdown then uses that information to kill running
services in the opposite order that they were started.

Bug: 64067984
Test: Boot and reboot bullhead

Change-Id: I6b4cacb03aed2a72ae98a346bce41ed5434a09c2