[applets/systemtray] Increase height of popup a bit

This generally improves things for applets that can display a lot of
data, which are now less likely to become scrollable.

BUG: 417374
FIXED-IN: 5.20

applets/systemtray/package/contents/ui/ExpandedRepresentation.qml

@@ -29,7 +29,7 @@ Item {
     id: popup
     //set width/height to avoid useless Dialog resize
     readonly property int defaultWidth: units.gridUnit * 24
-    readonly property int defaultHeight: units.gridUnit * 21
+    readonly property int defaultHeight: units.gridUnit * 24
 
     width: defaultWidth
     Layout.minimumWidth: defaultWidth