Use connected boolean as NLS does vs IBinder

To determine if the CPS can get/send messages. Apparently
the IBinder can be cached in ActivityManager and onBind() is not
always called when a service is connected the second time.

Test: manual; ensure a service recieves an onsubscribe for an
active rule post requestUnbind/requestRebind
Fixes: 62584038

Change-Id: Iffe37242509f3bf26e609e6b423f3928c00156ad
(cherry picked from commit 265d093c)