Replace Makara with an initial Rails 6 role based splitting method.

app/models/application_record.rb

@@ -1,6 +1,10 @@
 # frozen_string_literal: true
 
 class ApplicationRecord < ActiveRecord::Base
+  connects_to database: {
+    writing: :master,
+    reading: :slave1
+  }
   self.abstract_class = true
   include Remotable
 end