Fix leak of arbitrary statuses through unfavourite action in REST API (#13161)

app/controllers/api/v1/statuses/reblogged_by_accounts_controller.rb

@@ -66,8 +66,7 @@ class Api::V1::Statuses::RebloggedByAccountsController < Api::BaseController
     @status = Status.find(params[:status_id])
     authorize @status, :show?
   rescue Mastodon::NotPermittedError
-    # Reraise in order to get a 404 instead of a 403 error code
-    raise ActiveRecord::RecordNotFound
+    not_found
   end
 
   def pagination_params(core_params)