Respect DONT_KILL_APP flag when bringing down a disabled service.

Commit 540e123b introduce logic to clean up states when a component is
disabled. For services this included marking the process running the
service as removed so it can be killed later. However, this wasn't
respecting the Intent.EXTRA_DONT_KILL_APP flag where the caller
doesn't want the process of the disabled component to be killed.
This change now takes the flag into account.

Bug: 23491822
Bug: 15804187
Change-Id: I54a6e03cd66164dc8c4606a3c462114fe661ea8e