Add disconnect_hid_channels_serially flag

This to make sure the HID interrupt channel is properly disconnected
before the control channel disconnection is attempted.
Refer to the corresponding CL: aosp/3382047

Bug: 387937345
Bug: 315241296
Test: m -j
Flag: com.android.bluetooth.flags.disconnect_hid_channels_serially

Change-Id: Iefe35fd37fa152dd0f7954ac68ca1ffb93d58567