Lower the BLE connection supervision timeout to 5s.

This is the other part of the original change
(https://android-review.googlesource.com/333843) to lower the
connection supervision timeout to 5s.

This will take effect when an app requests a connection parameter
update through BluetoothGatt's requestConnectionPriority method after
the BLE connection has been established.

This makes sure that we do not revert back to a connection supervision
timeout of 20s in case the requestConnectionPriority method is called.

Change-Id: I66cdfcdd7b390b2858a4ab4362debc87bba45978