Client: Always close popups when hiding a window

It's not just popups that may have popups open on them. Always close open
popups when hiding a window to prevent dangling pointers.

[ChangeLog][QPA plugin] Fixed a crash when re-showing a popup after hiding its
parent.

Fixes: QTBUG-80562
Change-Id: I7cdac5c7a30e0add5ebf00259401e4d74626ce96
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>
Reviewed-by: David Edmundson <davidedmundson@kde.org>

src/plugins/platforms/wayland/qwaylandwindow.cpp

@@ -426,8 +426,7 @@ void QWaylandWindow::setVisible(bool visible)
         // QWaylandShmBackingStore::beginPaint().
     } else {
         sendExposeEvent(QRect());
-        if (window()->type() == Qt::Popup)
-            closePopups(this);
+        closePopups(this);
         reset();
     }
 }