chore: Change primary actor to Conversation for all the notification types. (#8435)

spec/jobs/migration/remove_message_notifications_spec.rb

@@ -0,0 +1,10 @@
+require 'rails_helper'
+
+RSpec.describe Migration::RemoveMessageNotifications do
+  subject(:job) { described_class.perform_later }
+
+  it 'enqueues the job' do
+    expect { job }.to have_enqueued_job(described_class)
+      .on_queue('scheduled_jobs')
+  end
+end