[FIX] im_livechat: clean live chat template

Before this PR, the external live chat templates contained useless
parts, residus of the old live chat implementation. This makes the
live chat code harder to understand and to maintain. This PR removes
those outdated parts.

task-3852092

closes odoo/odoo#137574

Signed-off-by: Sébastien Theys (seb) <seb@odoo.com>

addons/im_livechat/views/im_livechat_channel_templates.xml

@@ -19,6 +19,10 @@
                     <!-- Call the external Bundle to render the css, js, and js loader tags -->
                     <t t-out="channel.script_external"/>
 
+                    <script>
+                        window.odoo ??= {};
+                        window.odoo.csrf_token = "<t t-out="request.csrf_token(None)"/>";
+                    </script>
                     <style type="text/css">
                         body {
                             height: 100%;
@@ -89,9 +93,7 @@
         <template id="loader" name="Livechat : Javascript appending the livechat button">
             <t t-translation="off">
                 if (!window.odoo) {
-                    window.odoo = {
-                        csrf_token: "<t t-out="request.csrf_token(None)"/>",
-                    };
+                    window.odoo = {};
                 }
                 odoo.__session_info__ = Object.assign(odoo.__session_info__ || {}, {
                     livechatData: {