[ActivityManager] Improve multi-thread access the same provider

Application may use many threads to load data from provider.
If the target provider needs to start process, each access
will occupy one binder thread of system server until the
provider process started and published.

Sometimes application uses more than 16 threads to access
the same provider, and the provider process needs a little
long time to start, then all binder threads of system server
are waiting. But when the provider is ready, it is unable to
publish to notify those waiting threads because no availabe
binder thread to use. And device will become almost hang.

Improvement:
If there is already a thread acquiring provider, let other threads
(which try to acquire the same provider) wait the result of the
first one. That reduces IPC to save binder thread of system server.

Remove calling removeContentProvider in installProvider because
we have ensured only get one provider holder for the same provider,
the original race that gets a new useless holder will not happen.

Change-Id: I521f2603db8ced56912f5dc54342a70451e68381