Remove obsolete devise-async gem, switch to built-in async email delivery (#7643)

Gemfile

@@ -81,9 +81,6 @@ gem 'aws-sdk-lambda'
 gem 'aws-sdk-rails'
 gem 'aws-sdk-s3'
 gem 'delayed_job_active_record'
-gem 'devise-async',
-    git: 'https://github.com/mhfs/devise-async.git',
-    branch: 'devise-4.x'
 gem 'image_processing'
 gem 'img2zpl', git: 'https://github.com/scinote-eln/img2zpl'
 gem 'rufus-scheduler'

Gemfile.lock

@@ -5,14 +5,6 @@ GIT
     sneaky-save (0.1.3)
       activerecord (>= 3.2.0)
 
-GIT
-  remote: https://github.com/mhfs/devise-async.git
-  revision: 177f6363a002f7ff28f1d289c8cab7ad8d9cb8c5
-  branch: devise-4.x
-  specs:
-    devise-async (0.10.2)
-      devise (>= 4.0)
-
 GIT
   remote: https://github.com/scinote-eln/canaid
   revision: bba1b817d1c9b0c7e0440a83d0f62848aabc0a1b

app/models/user.rb

@@ -8,7 +8,7 @@ class User < ApplicationRecord
   include ActiveStorageConcerns
 
   devise :invitable, :confirmable, :database_authenticatable, :registerable,
-         :async, :recoverable, :rememberable, :trackable, :validatable,
+         :recoverable, :rememberable, :trackable, :validatable,
          :timeoutable, :omniauthable, :lockable,
          omniauth_providers: Extends::OMNIAUTH_PROVIDERS,
          stretches: Constants::PASSWORD_STRETCH_FACTOR
@@ -635,6 +635,10 @@ class User < ApplicationRecord
     Rails.configuration.x.core_api_key_enabled
   end
 
+  def send_devise_notification(notification, *args)
+    devise_mailer.send(notification, self, *args).deliver_later
+  end
+
   protected
 
   def confirmation_required?

config/initializers/devise_async.rb

@@ -1,4 +0,0 @@
-Devise::Async.enabled = true
-Devise::Async.backend = :delayed_job
-Devise::Async.queue = :devise_email
-# Devise::Async.priority = 10