Change unauthenticated responses to be cached in REST API (#24348)

app/controllers/api/v1/custom_emojis_controller.rb

@@ -1,8 +1,10 @@
 # frozen_string_literal: true
 
 class Api::V1::CustomEmojisController < Api::BaseController
+  vary_by ''
+
   def index
-    expires_in 3.minutes, public: true
+    cache_even_if_authenticated!
     render_with_cache(each_serializer: REST::CustomEmojiSerializer) { CustomEmoji.listed.includes(:category) }
   end
 end