Use NULL for nick/blurb in GObject params

As they are only used by gstreamer for gst-inspect & other tools.
Projects like Mutter/gtk have completely dropped them as well, so follow
their path

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/3505>

js/ui/layout.js

@@ -39,15 +39,15 @@ function isPopupMetaWindow(actor) {
 export const MonitorConstraint = GObject.registerClass({
     Properties: {
         'primary': GObject.ParamSpec.boolean(
-            'primary', 'Primary', 'Track primary monitor',
+            'primary', null, null,
             GObject.ParamFlags.READABLE | GObject.ParamFlags.WRITABLE,
             false),
         'index': GObject.ParamSpec.int(
-            'index', 'Monitor index', 'Track specific monitor',
+            'index', null, null,
             GObject.ParamFlags.READABLE | GObject.ParamFlags.WRITABLE,
             -1, 64, -1),
         'work-area': GObject.ParamSpec.boolean(
-            'work-area', 'Work-area', 'Track monitor\'s work-area',
+            'work-area', null, null,
             GObject.ParamFlags.READABLE | GObject.ParamFlags.WRITABLE,
             false),
     },