fix(backend): fix sending N notifications to a single conversation participant

Because of the conversation participant ID being necessary in the email, we launch N jobs to send
notifications, so we need to send the email straight away.

Anonymous participants are always only a single conversation actor
participant, so we're fine

Closes #1384

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/mobilizon/events/events.ex

@@ -792,7 +792,7 @@ defmodule Mobilizon.Events do
     end
   end
 
-  def get_participant(event_id, actor_id, %{}) do
+  def get_participant(event_id, actor_id, _params) do
     case Participant
          |> Repo.get_by(event_id: event_id, actor_id: actor_id)
          |> Repo.preload(@participant_preloads) do