[KCMs/Activities] Fix jagginess for activities list icons on high DPI systems

BUG: 414945
FIXED-IN: 5.17.5

kcms/activities/qml/activitiesTab/ActivitiesView.qml

@@ -52,6 +52,8 @@ ColumnLayout {
                         height: Kirigami.Units.iconSizes.medium
                         width: height
                         source: model.icon
+                        sourceSize.width: model.icon.width
+                        sourceSize.height: model.icon.height
                     }
 
                     QQC2.Label {