Fake accessibility service used by UiAutomation not destroyed.

UiAutomation registers a fake accessibility service to introspect
the screen. Upon the death of the shell process that started an
instrumentation in which a UiAutomation resides the connection
between the UiAutomation and the system is kept alive allowing
the instrumentation to introspect the screen even after the death
of the shell process.

bug:8285905

Change-Id: I1a16d78abbea032116c4baed175cfc0d5dedbf0c