Remove string attribute from views

issue2350

view/update_cost_price_ask_form.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <!-- This file is part of Tryton.  The COPYRIGHT file at the top level of
 this repository contains the full copyright notices and license terms. -->
-<form string="Update Cost Price" cursor="cost_price">
+<form cursor="cost_price">
     <group id="label_product_template" col="1" xexpand="0">
         <label name="template"/>
         <label name="product"/>

view/update_cost_price_show_move_form.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <!-- This file is part of Tryton.  The COPYRIGHT file at the top level of
 this repository contains the full copyright notices and license terms. -->
-<form string="Update Cost Price - Move">
+<form>
     <label name="description"/>
     <field name="description" colspan="3"/>
     <label name="journal"/>