Don't update last_buffered timestamp when creating a suggested tweet (#12537)

* Don't update last_buffered timestamp when creating a suggested tweet

* Downcase email instead to rely on index

app/controllers/admin/invitations_controller.rb

@@ -12,7 +12,7 @@ module Admin
       email = params.dig(:user, :email)
       name = params.dig(:user, :name)
 
-      if User.exists?(["lower(email) = ? AND registered = ?", email, true])
+      if User.exists?(email: email.downcase, registered: true)
         flash[:error] = "Invitation was not sent. There is already a registered user with the email: #{email}"
         redirect_to admin_invitations_path
         return

app/controllers/buffer_updates_controller.rb

@@ -7,7 +7,6 @@ class BufferUpdatesController < ApplicationController
     create_main_tweet
     create_satellite_tweets
     create_facebook_post
-    @article.update(last_buffered: Time.current)
     redirect_back(fallback_location: "/mod")
   end