Fix digest email processing, consolidate Oban queues

The email related jobs can all share a single Oban queue

changelog.d/digest_emails.fix

@@ -0,0 +1 @@
+Fix the processing of email digest jobs.

config/config.exs

@@ -590,7 +590,6 @@
     background: 5,
     remote_fetcher: 2,
     attachments_cleanup: 1,
-    new_users_digest: 1,
     mute_expire: 5
   ],
   plugins: [Oban.Plugins.Pruner],

lib/pleroma/workers/cron/digest_emails_worker.ex

@@ -7,7 +7,7 @@ defmodule Pleroma.Workers.Cron.DigestEmailsWorker do
   The worker to send digest emails.
   """
 
-  use Oban.Worker, queue: "digest_emails"
+  use Oban.Worker, queue: "mailer"
 
   alias Pleroma.Config
   alias Pleroma.Emails

lib/pleroma/workers/cron/new_users_digest_worker.ex

@@ -9,7 +9,7 @@ defmodule Pleroma.Workers.Cron.NewUsersDigestWorker do
 
   import Ecto.Query
 
-  use Pleroma.Workers.WorkerHelper, queue: "new_users_digest"
+  use Pleroma.Workers.WorkerHelper, queue: "mailer"
 
   @impl Oban.Worker
   def perform(_job) do

priv/repo/migrations/20231107200724_consolidate_email_queues.exs

@@ -0,0 +1,9 @@
+defmodule Pleroma.Repo.Migrations.ConsolidateEmailQueues do
+  use Ecto.Migration
+
+  def change do
+    execute(
+      "UPDATE oban_jobs SET queue = 'mailer' WHERE queue in ('digest_emails', 'new_users_digest')"
+    )
+  end
+end