Allow multiple outgoing HID connections

After successful pairing and service discovery, profile connections are
initiated. Default transport for HID host is BR/EDR, so it initiates
BR/EDR HID connection. The settings app decides to use LE transport and
calls BluetoothHidHost.setPreferredTransport() with LE transport. This
triggers the HID host service into requesting disconnection over BR/EDR
and connection over LE.
Since BTA HH does not offer any interface for cancelling the connection,
the disconnection request gets ignored. And since BTIF HH is in
connection state, the connection request also gets ignored.

Test: mmm packags/modules/Bluetooth
Test: Pair with earbuds supporting both DSA 1.0 and DSA 2.0
Flag: com.android.bluetooth.flags.initiate_multiple_hid_connections
Bug: 347241319
Bug: 356141637
Change-Id: I5d2d054e64704c4ee4a6d7c9dd16a0fdb8138d19