[Bugfix][Media] Fix ISessionControllerCallback leaks in the system_server when the far side died

When the far side died unexpectedly, it will not call unregisterCallback, resulting in callbacks leak in system_server. Eventually, the system_server will reboot because of too many BinderProxies leaks.

Test: manual

Change-Id: I1d99ea35b8bbbb92db648bbf68c267dce435110c