Revert "Optimize Site#each_site_file (#9187)"

This reverts commit b2891a4.

lib/jekyll/site.rb

@@ -360,9 +360,15 @@ def documents
     end
 
     def each_site_file
-      pages.each { |page| yield page }
-      static_files.each { |file| yield(file) if file.write? }
-      collections.each_value { |coll| coll.docs.each { |doc| yield(doc) if doc.write? } }
+      seen_files = []
+      %w(pages static_files_to_write docs_to_write).each do |type|
+        send(type).each do |item|
+          next if seen_files.include?(item)
+
+          yield item
+          seen_files << item
+        end
+      end
     end
 
     # Returns the FrontmatterDefaults or creates a new FrontmatterDefaults