Disable autodetection when the debugger is set up by the SDKtool

This is save now, since the SDKtool will have set up a proper debugger
and if it did not fill in one, then the whole widget will stay editable,
even for auto-detected kits.

Task-number: QTCREATORBUG-9529
Change-Id: I92e89f74a1dd27705d34f77d19d521c69067eb2d
Reviewed-by: hjk <hjk121@nokiamail.com>