ohos: adapt the bluetooth autotests to the OHOS backend

OHOS exposes no local adapter address, so QBluetoothLocalDevice reports
a null one and the tests asserting a non-null address cannot pass on the
platform. Skip them instead, so that a platform limitation is not
reported as a test failure.

This backend implements RFCOMM sockets only, so reuse the existing
exclusion of the L2CAP protocol from the service info assignment data.
Join the platforms whose socket defaults to a secure connection, which
QBluetoothSocketPrivateOhos does.

Task-number: QTBUG-147192
Pick-to: 6.12
Change-Id: I4518b0d4aaddfd296f0df3f147dd4bcde7046a34
Reviewed-by: Zbigniew Chyla <zbigniew.chyla@qt.io>
Reviewed-by: Liang Qi <liang.qi@qt.io>