[ActivityManager] Avoid unnecessary restart provider process

Caller C accesses provider P. Both processes of C and P died
before P publishes, P will still be restarted even there is
no connection because P is in mLaunchingProviders.
When device is low memory, the restarting provider process
may be killed easily before publish because no caller to raise
its oom-adj. Then device will busy keeping restart it.

Solution:
If there is no connection to the provider, do not restart it.

Change-Id: If6f2d2258d78b6c0989c6e5f3e0cad14db821464
(cherry picked from commit fb90eb27)