Fix clicking in test_navigationRequested

The second mouse click in the test was handled as a double click.
Workaround the issue by changing click coordinate in the initialization.

Task-number: QTBUG-56180
Change-Id: I12e94ed5dbccdde4c0e6335e8a1c8a5e59b2d6a6
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>