feat: add index migration (#7050)

db/migrate/20230510060828_add_index_to_messages_for_reportings.rb

@@ -0,0 +1,7 @@
+class AddIndexToMessagesForReportings < ActiveRecord::Migration[7.0]
+  disable_ddl_transaction!
+  def change
+    add_index :messages, [:conversation_id, :account_id, :message_type, :created_at], name: 'index_messages_on_conversation_account_type_created',
+                                                                                      algorithm: :concurrently
+  end
+end