kcms/users: improve UI for the case where no real name is set

Currently the title of the list item is blank, leaving an awkward
subtitle with nothing above it. This commit improves that to use the
username as the title and avoid setting the subtitle at all, in the case
where the user has not provided their real name.

BUG: 441821
FIXED-IN: 5.23

kcms/users/package/contents/ui/main.qml

@@ -56,8 +56,9 @@ KCM.ScrollViewKCM {
         }
 
         delegate: Kirigami.BasicListItem {
-            text: model.display
-            subtitle: model.name
+            text: model.display ? model.display : model.name
+            subtitle: model.display ? model.name : ""
+            reserveSpaceForSubtitle: true
 
             highlighted: index == userList.currentIndex
 
@@ -80,7 +81,7 @@ KCM.ScrollViewKCM {
                 Kirigami.Avatar {
                     source: model.decoration + '?' + avatarVersion // force reload after saving
                     cache: false // avoid caching
-                    name: model.display
+                    name: model.display ? model.display : model.name
                     anchors {
                         fill: parent
                         margins: 1