Camera: Limit the scope 'mTrackerLock' within 'disconnectImpl'

'disconnectImpl' holds 'mTrackerLock' for its entire scope.
This is not needed and could lead to deadlocks in case the
request thread encounters errors and tries to clean up
any failed requests. In this scenario the request thread will
already hold 'mInflightLock' and then try to acquire
'mTrackerLock' as well. The 'disconnectImpl' context will
acquire 'mTrackerLock' first and at some later point try to
get 'mInflightLock' which will end up in a deadlock.
To avoid this, limit the scope of 'mTrackerLock' within
'disconnectImpl'. The lock purpose is to protect other threads
from accessing invalid 'mStatusTracker' instances and must not
introduce side effects.

Bug: 115784704
Test: Camera CTS, Manual test

Change-Id: I96b039cb454e0c185ecdf0c8072a9494233c1169