Convert more flow tests to replay/compare (#1009)

* Convert more flow tests to replay/compare

Add the replay extension to another batch of flow tests.  In the course of
this:

- Refactor out domain deletion code into DatabaseHelper so that it can be used
  from multiple tests.
- Make null handling uniform for contact phone numbers.

* Convert postLoad method to onLoad.

* Remove "Test" import missed during rebase

* Deal with persistence of billing cancellations

Deal with the persistence of billing cancellations, which were added in the
master branch since before this PR was initially sent for review.

* Adding forgotten flyway file

* Removed debug variable

db/src/main/resources/sql/flyway/V88__transfer_billing_cancellation_history_id.sql

@@ -0,0 +1,18 @@
+-- Copyright 2021 The Nomulus Authors. All Rights Reserved.
+--
+-- Licensed under the Apache License, Version 2.0 (the "License");
+-- you may not use this file except in compliance with the License.
+-- You may obtain a copy of the License at
+--
+--     http://www.apache.org/licenses/LICENSE-2.0
+--
+-- Unless required by applicable law or agreed to in writing, software
+-- distributed under the License is distributed on an "AS IS" BASIS,
+-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+-- See the License for the specific language governing permissions and
+-- limitations under the License.
+
+ALTER TABLE "Domain"
+    ADD COLUMN  "transfer_billing_cancellation_history_id" int8;
+ALTER TABLE "DomainHistory"
+    ADD COLUMN  "transfer_billing_cancellation_history_id" int8;