[FIX] estate: fixing code guidance issue of field

Author: ybenbrai

estate/views/estate_property_offer_views.xml

@@ -34,7 +34,7 @@
                 <field name="price"/>
                 <field name="partner_id"/>
                 <field name="property_type_id"/>
-                <field name="state" invisible="1"/>
+                <field name="state" optional="hidden"/>
                 <field name="validity"/>
                 <field name="date_deadline"/>
                 <button name="action_accept" type="object" icon="fa-check" title="Accept" invisible="state"/>

estate/views/estate_property_type_views.xml

@@ -43,7 +43,7 @@
                     </group>
                     <group string="Offers" colspan="2">
                         <field name="offer_count"/>
-                        <field name="offer_ids" invisible="1"/>
+                        <field name="offer_ids" optional="hidden"/>
                     </group>
                 </sheet>
             </form>