Fix invalid/empty RSS feed link on account pages (#20772)

Fixes #20770

app/controllers/accounts_controller.rb

@@ -17,6 +17,8 @@ class AccountsController < ApplicationController
     respond_to do |format|
       format.html do
         expires_in 0, public: true unless user_signed_in?
+
+        @rss_url = rss_url
       end
 
       format.rss do