android/gatt: Factor out unregistering client into helper function
android/gatt: Factor out unregistering client into helper function

This will be also used by test interface.

mapfau/bluez,pkarasev3/bluez,silent-snowman/bluez,mapfau/bluez,ComputeCycles/bluez,pkarasev3/bluez,pkarasev3/bluez,pstglia/external-bluetooth-bluez,pstglia/external-bluetooth-bluez,mapfau/bluez,pstglia/external-bluetooth-bluez,silent-snowman/bluez,ComputeCycles/bluez,pkarasev3/bluez,ComputeCycles/bluez,pstglia/external-bluetooth-bluez,mapfau/bluez,silent-snowman/bluez,ComputeCycles/bluez,silent-snowman/bluez