Fix /api/v1/custom_emojis being cached even when unauthenticated API access is disallowed (#24665)

app/controllers/api/v1/custom_emojis_controller.rb

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