When the test is showing the error message over and over, it's not
waiting for the native dialog to actually become visible, and as
a result, hiding it has no effect and won't result in a call
to processResponse, where we got rid of the native dialog.
To fix this we explicitly release the native dialog when
encountering this corner case.
Add logic to QErrorMessage to test both native and non
native dialogs.
Pick-to: 6.5
Change-Id: I19ac3f463997aed1e66f646fdfcbb4d2459116d1
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
349fda471e