Try and clean up desktop update needles a bit

The 'desktop_pacakge_tool_update-kde-detected' needles and
'desktop_update_notification_systray-kde' needles are actually
matching on exactly the same thing, so drop the redundancy. We
need to have the desktop_package_tool_update tag on the older
(F33) version of this needle because on F33 we click on it to
launch the update tool in the desktop_update_graphical test; from
F34 onwards this is *not* what we want to do so the needle should
not have that tag to avoid throwing the test off. When F33 goes
EOL we can drop that tag from the needle and simplify the
destop_update_graphical test. Also add a needle for the Discover
app's 'update' icon when no updates are found.

Signed-off-by: Adam Williamson <awilliam@redhat.com>

needles/kde/desktop_package_tool_update-kde-detected-20190821.json

@@ -1,17 +0,0 @@
-{
-  "area": [
-    {
-      "xpos": 753,
-      "width": 19,
-      "type": "match",
-      "ypos": 741,
-      "height": 18,
-      "match": 90
-    }
-  ],
-  "properties": [],
-  "tags": [
-    "DESKTOP-kde",
-    "desktop_package_tool_update"
-  ]
-}

needles/kde/desktop_package_tool_update-kde-detected-20190918.json

@@ -1,17 +0,0 @@
-{
-  "area": [
-    {
-      "width": 19,
-      "type": "match",
-      "height": 18,
-      "ypos": 741,
-      "xpos": 779,
-      "match": 90
-    }
-  ],
-  "properties": [],
-  "tags": [
-    "DESKTOP-kde",
-    "desktop_package_tool_update"
-  ]
-}

needles/kde/desktop_package_tool_update-kde-detected-20210218.json

@@ -1,16 +0,0 @@
-{
-  "area": [
-    {
-      "height": 18,
-      "ypos": 738,
-      "xpos": 745,
-      "width": 19,
-      "type": "match"
-    }
-  ],
-  "properties": [],
-  "tags": [
-    "DESKTOP-kde",
-    "desktop_package_tool_update"
-  ]
-}

needles/kde/desktop_package_tool_update-kde-noupdates-20210614.json

@@ -1,9 +1,9 @@
 {
   "area": [
     {
-      "xpos": 756,
-      "ypos": 738,
       "height": 18,
+      "xpos": 9,
+      "ypos": 545,
       "type": "match",
       "width": 19
     }

needles/kde/desktop_update_notification_systray-kde-20200929.json

@@ -11,6 +11,7 @@
     ],
     "properties": [],
     "tags": [
-        "desktop_update_notification_systray"
+        "desktop_update_notification_systray",
+        "desktop_package_tool_update"
     ]
 }

tests/desktop_update_graphical.pm

@@ -16,6 +16,9 @@ sub run {
     desktop_vt;
 
     # run the updater
+    # FIXME: when F33 goes EOL, remove all the KDE < F34 stuff below
+    # and drop 'desktop_package_tool_update' tag from
+    # desktop_update_notification_systray-kde-20200929.json
     if ($desktop eq 'kde') {
         # KDE team tells me until F34 the 'preferred' update method
         # was the systray applet...