ohos: declare the bluetooth switch dialog blocking the autotests

OHOS asks the user before it turns Bluetooth on or off and the prompt
cannot be suppressed, so tst_QBluetoothLocalDevice stalled on it and
could only pass while somebody watched the device and tapped. Declare
the dialog and the button that gets past it, so harmonyostestrunner
answers it for every test that links this module.

Press the rightmost button: the dialog labels both of its buttons
"Enable" or both "Disable", so nothing but their position tells the
affirmative one from the one that cancels.

Task-number: QTBUG-149351
Pick-to: 6.12
Change-Id: I9eedf6fe74270651732d5a35468d8cc1e915f079
Reviewed-by: Zbigniew Chyla <zbigniew.chyla@qt.io>
Reviewed-by: Liang Qi <liang.qi@qt.io>