Remove CacheBuster default options (#30718)

app/lib/cache_buster.rb

@@ -2,13 +2,8 @@
 
 class CacheBuster
   def initialize(options = {})
-    Rails.application.deprecators[:mastodon].warn('Default values for the cache buster secret header name and values will be removed in Mastodon 4.3. Please set them explicitely if you rely on those.') unless options[:http_method] || (options[:secret] && options[:secret_header])
-
-    @secret_header = options[:secret_header] ||
-                     (options[:http_method] ? nil : 'Secret-Header')
-    @secret = options[:secret] ||
-              (options[:http_method] ? nil : 'True')
-
+    @secret_header = options[:secret_header]
+    @secret = options[:secret]
     @http_method = options[:http_method] || 'GET'
   end