[FIX] mail_tracking: mixed classes

In migration #873 the classes DiscussController and MailController which
are the result of an upstream functionality split are merge altogether
in this module override causing undesired side effects in other modules
trying to extend those (i.e.: portal)

TT41432

mail_tracking/controllers/__init__.py

@@ -1,3 +1,4 @@
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
 
 from . import main
+from . import discuss

mail_tracking/controllers/discuss.py

@@ -0,0 +1,24 @@
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
+from odoo import http
+
+from odoo.addons.mail.controllers.discuss import DiscussController
+
+
+class MailTrackingDiscussController(DiscussController):
+    @http.route()
+    def mail_init_messaging(self):
+        """Route used to initial values of Discuss app"""
+        values = super().mail_init_messaging()
+        values.update(
+            {"failed_counter": http.request.env["mail.message"].get_failed_count()}
+        )
+        return values
+
+    @http.route("/mail/failed/messages", methods=["POST"], type="json", auth="user")
+    def discuss_failed_messages(self, max_id=None, min_id=None, limit=30, **kwargs):
+        return http.request.env["mail.message"]._message_fetch(
+            domain=[("is_failed_message", "=", True)],
+            max_id=max_id,
+            min_id=min_id,
+            limit=limit,
+        )

mail_tracking/controllers/main.py

@@ -10,7 +10,6 @@ import werkzeug
 import odoo
 from odoo import SUPERUSER_ID, api, http
 
-from odoo.addons.mail.controllers.discuss import DiscussController
 from odoo.addons.mail.controllers.mail import MailController
 
 _logger = logging.getLogger(__name__)
@@ -30,7 +29,7 @@ def db_env(dbname):
     yield api.Environment(cr, SUPERUSER_ID, {})
 
 
-class MailTrackingController(MailController, DiscussController):
+class MailTrackingController(MailController):
     def _request_metadata(self):
         """Prepare remote info metadata"""
         request = http.request.httprequest
@@ -97,21 +96,3 @@ class MailTrackingController(MailController, DiscussController):
         response.mimetype = "image/gif"
         response.data = base64.b64decode(BLANK)
         return response
-
-    @http.route()
-    def mail_init_messaging(self):
-        """Route used to initial values of Discuss app"""
-        values = super().mail_init_messaging()
-        values.update(
-            {"failed_counter": http.request.env["mail.message"].get_failed_count()}
-        )
-        return values
-
-    @http.route("/mail/failed/messages", methods=["POST"], type="json", auth="user")
-    def discuss_failed_messages(self, max_id=None, min_id=None, limit=30, **kwargs):
-        return http.request.env["mail.message"]._message_fetch(
-            domain=[("is_failed_message", "=", True)],
-            max_id=max_id,
-            min_id=min_id,
-            limit=limit,
-        )