Remove duplicate object IDs in dialog-ab.glade

Found by gtk-builder-tool validate

.../dialog-ab.glade:1665:1 Duplicate object ID 'dialog-vbox3' (previously on line 573)
.../dialog-ab.glade:1670:1 Duplicate object ID 'dialog-action_area3' (previously on line 578)

gnucash/import-export/aqb/dialog-ab.glade

@@ -1661,12 +1661,12 @@
     <property name="title" translatable="yes">Select File Import Format and Template</property>
     <property name="type-hint">dialog</property>
     <child internal-child="vbox">
-      <object class="GtkBox" id="dialog-vbox3">
+      <object class="GtkBox" id="dialog-vbox4">
         <property name="visible">True</property>
         <property name="can-focus">False</property>
         <property name="orientation">vertical</property>
         <child internal-child="action_area">
-          <object class="GtkButtonBox" id="dialog-action_area3">
+          <object class="GtkButtonBox" id="dialog-action_area4">
             <property name="visible">True</property>
             <property name="can-focus">False</property>
             <property name="layout-style">end</property>