Remove unused message for analytic required on quotation

The error using it was removed in changeset f160c38addd9.

message.xml

@@ -1,10 +0,0 @@
-<?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. -->
-<tryton>
-    <data group="1">
-        <record model="ir.message" id="msg_analytic_account_required_for_quotation">
-            <field name="text">To get a quote for purchase "%(purchase)s", you must enter a analytic account for "%(roots)s" on line "%(line)s".</field>
-        </record>
-    </data>
-</tryton>

tryton.cfg

@@ -6,4 +6,3 @@ depends:
     purchase
 xml:
     purchase.xml
-    message.xml