Change hashtag trends to be stored in the database instead of redis (#32837)

Co-authored-by: David Roetzel <david@roetzel.de>

spec/mailers/admin_mailer_spec.rb

@@ -71,6 +71,7 @@ RSpec.describe AdminMailer do
     before do
       PreviewCardTrend.create!(preview_card: link)
       StatusTrend.create!(status: status, account: Fabricate(:account))
+      TagTrend.create!(tag: tag)
       recipient.user.update(locale: :en)
     end