Windows: don't warn when a device is invalidated during format probing

The format probe runs asynchronously on a thread pool, so the endpoint
can disappear between enumeration and IMMDevice::Activate(), e.g. on
Bluetooth/USB/HDMI hot-unplug or the device being disabled.
Activate() then fails with AUDCLNT_E_DEVICE_INVALIDATED, which is an
expected condition, so log it to the probes category instead of
emitting a warning.

For other failures, use audioClientErrorString() rather than
QSystemError::windowsComString(), which can't resolve AUDCLNT_* codes
and printed "Unknown error 0x88890004".

Pick-to: 6.12
Change-Id: Ic9e0e7b2bddd5f57747a37aeabdfd6d2d7b48f9e
Reviewed-by: Tim Blechmann <tim.blechmann@qt.io>