Screen grabber: hide() the flyout at first

I don't remember why I did show() at first, but works fine without, and
fixes the issue of a 1px wide flyout showing up somewhere in the
chatform

src/widget/tool/flyoutoverlaywidget.cpp

@@ -34,7 +34,7 @@ FlyoutOverlayWidget::FlyoutOverlayWidget(QWidget *parent)
     
     connect(animation, &QAbstractAnimation::finished, this, &FlyoutOverlayWidget::finishedAnimation);
     setFlyoutPercent(0);
-    show();
+    hide();
     
 }