More a11y test updates

The headerbar test and the buttons tests changed because we've
recently changed accessible names, descriptions and roles of
GtkHeaderBar and GtkSwitch.

testsuite/a11y/buttons.txt

@@ -20,7 +20,6 @@ window1
       parent: grid1
       index: 0
       name: Test switch
-      description: Switches between on and off states
       state: enabled focusable sensitive showing visible
       toolkit: gtk
       <AtkComponent>
@@ -33,8 +32,6 @@ window1
       "toggle button"
       parent: grid1
       index: 1
-      name: Switch
-      description: Switches between on and off states
       state: checked enabled focusable sensitive showing visible
       toolkit: gtk
       <AtkComponent>

testsuite/a11y/headerbar.txt

@@ -7,7 +7,7 @@ window1
   layer: window
   alpha: 1
   headerbar1
-    "filler"
+    "panel"
     parent: window1
     index: 0
     state: enabled sensitive showing visible