Normalize wizard message views

We use the proper icon between info, question, warning and error.
We remove the exclamation mark in info messages.

issue9429
review301831002

view/purchase_request_create_start_form.xml

@@ -2,7 +2,7 @@
 <!-- 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 col="2">
-    <image name="tryton-info" xexpand="0" xfill="0"/>
+    <image name="tryton-question" xexpand="0" xfill="0"/>
     <label string="Create Purchase Requests?" id="create"
         yalign="0.0" xalign="0.0" xexpand="1"/>
 </form>

view/supply_start_form.xml

@@ -2,7 +2,7 @@
 <!-- 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 col="2">
-    <image name="tryton-info" xexpand="0" xfill="0"/>
+    <image name="tryton-question" xexpand="0" xfill="0"/>
     <label string="Supply Stock?" id="supply"
         yalign="0.0" xalign="0.0" xexpand="1"/>
 </form>