officejs_support_request_ui: use preferred number of lines for RSS listbox

default of 5 is not enough and must have caused people to miss messages ( when more than 5 messages are posted between 2 refreshes from their RSS reader)

bt5/erp5_officejs_support_request_ui/SkinTemplateItem/portal_skins/erp5_officejs_support_request/SupportRequestModule_viewLastSupportRequestListAsRss/listbox.xml

@@ -20,7 +20,6 @@
                 <string>editable_columns</string>
                 <string>global_search_column</string>
                 <string>hide_rows_on_no_search_criterion</string>
-                <string>lines</string>
                 <string>list_method</string>
                 <string>portal_types</string>
                 <string>search_columns</string>
@@ -108,10 +107,6 @@
                     <key> <string>global_search_column</string> </key>
                     <value> <string></string> </value>
                 </item>
-                <item>
-                    <key> <string>lines</string> </key>
-                    <value> <string></string> </value>
-                </item>
                 <item>
                     <key> <string>list_method</string> </key>
                     <value> <string></string> </value>
@@ -240,10 +235,6 @@
                     <key> <string>hide_rows_on_no_search_criterion</string> </key>
                     <value> <int>0</int> </value>
                 </item>
-                <item>
-                    <key> <string>lines</string> </key>
-                    <value> <int>5</int> </value>
-                </item>
                 <item>
                     <key> <string>list_method</string> </key>
                     <value>