Testconfig: Reducing WinExtras stages

There is no need to execute all non-win stages for WinExtras
module, one linux and mac is enough.

Task-number: QTQAINFRA-772
Change-Id: I0c13732c47b5f81111a0b01b38a6bc4df0937f1b
Reviewed-by: Tony Sarajärvi <tony.sarajarvi@digia.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>
Reviewed-by: Sergio Ahumada <sergio.ahumada@digia.com>