Remove QQuickWindow::setClearBeforeRendering calls, gone in Qt6

We only set the default value anyway, so nothing lost here.

applets/kicker/plugin/dashboardwindow.cpp

@@ -19,7 +19,6 @@ DashboardWindow::DashboardWindow(QQuickItem *parent)
     , m_visualParentItem(nullptr)
     , m_visualParentWindow(nullptr)
 {
-    setClearBeforeRendering(true);
     setFlags(Qt::FramelessWindowHint);
 
     setIcon(QIcon::fromTheme(QStringLiteral("plasma")));

krunner/view.cpp

@@ -40,7 +40,6 @@ View::View(QWindow *)
     , m_offset(.5)
     , m_floating(false)
 {
-    setClearBeforeRendering(true);
     setColor(QColor(Qt::transparent));
     setFlags(Qt::FramelessWindowHint | Qt::WindowStaysOnTopHint);
 

ksplash/ksplashqml/splashwindow.cpp

@@ -43,7 +43,6 @@ SplashWindow::SplashWindow(bool testing, bool window, const QString &theme, QScr
     setScreen(screen);
     setColor(Qt::transparent);
     setDefaultAlphaBuffer(true);
-    setClearBeforeRendering(true);
     setResizeMode(KQuickAddons::QuickViewSharedEngine::SizeRootObjectToView);
 
     if (!m_window) {

logout-greeter/shutdowndlg.cpp

@@ -61,7 +61,6 @@ KSMShutdownDlg::KSMShutdownDlg(QWindow *parent, KWorkSpace::ShutdownType sdtype,
 // having a popup here has severe side effects.
 {
     // window stuff
-    setClearBeforeRendering(true);
     setColor(QColor(Qt::transparent));
     setScreen(screen);
 

shell/panelview.cpp

@@ -63,7 +63,6 @@ PanelView::PanelView(ShellCorona *corona, QScreen *targetScreen, QWindow *parent
         setScreen(targetScreen);
     }
     setResizeMode(QuickViewSharedEngine::SizeRootObjectToView);
-    setClearBeforeRendering(true);
     setColor(QColor(Qt::transparent));
     setFlags(Qt::FramelessWindowHint | Qt::WindowDoesNotAcceptFocus);
     updateAdaptiveOpacityEnabled();