tdf#91063 Move border to Gtkbox in Data Series content panel

Change-Id: I33dd8f0688df09e57d565f0f5fb2883297e0497f
Reviewed-on: https://gerrit.libreoffice.org/19607Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Yousuf Philips <philipz85@hotmail.com>

chart2/uiconfig/ui/sidebarseries.ui

@@ -5,13 +5,13 @@
   <object class="GtkGrid" id="ChartSeriesPanel">
     <property name="visible">True</property>
     <property name="can_focus">False</property>
-    <property name="border_width">6</property>
     <child>
       <object class="GtkBox" id="box1">
         <property name="visible">True</property>
         <property name="can_focus">False</property>
         <property name="orientation">vertical</property>
         <property name="spacing">6</property>
+        <property name="border_width">6</property>
         <child>
           <placeholder/>
         </child>