[13.0] Fixed context field get

On fetchmail_thread_default when creating a new mail.message it says the context["fetchmail_server_id"] is None, the field value is context["default_fetchmail_server_id"].

fetchmail_thread_default/models/mail_thread.py

@@ -18,7 +18,7 @@ class MailThread(models.AbstractModel):
         thread_id=None,
     ):
         server = self.env["fetchmail.server"].browse(
-            self.env.context.get("fetchmail_server_id")
+            self.env.context.get("default_fetchmail_server_id")
         )
         if server.default_thread_id and not (model or thread_id):
             model = server.default_thread_id._name

fetchmail_thread_default/tests/test_fetchmail.py

@@ -37,7 +37,7 @@ class FetchmailCase(SavepointCase):
         """An unbound incoming email gets posted to the sink."""
         # Imitate what self.server.feth_mail() would do
         result = self.MailThread.with_context(
-            fetchmail_server_id=self.server.id
+            default_fetchmail_server_id=self.server.id
         ).message_process(
             self.server.object_id.model,
             MAIL_TEMPLATE.format(