Implement changes suggested by testcontainer dev (#426)

* Implement changes suggested by testcontainer dev

See https://github.com/google/nomulus/issues/401
Specifically:
- Use getContainerIpAddress() instead of localhost to insulate us from
  off-machine docker usage.
- Remove shutdown hook to close the container, as testcontainers does this for
  us.

core/src/test/java/google/registry/model/transaction/JpaTransactionManagerRule.java

@@ -97,7 +97,6 @@ abstract class JpaTransactionManagerRule extends ExternalResource {
         new PostgreSQLContainer(NomulusPostgreSql.getDockerTag())
             .withDatabaseName(MANAGEMENT_DB_NAME);
     container.start();
-    Runtime.getRuntime().addShutdownHook(new Thread(() -> container.close()));
     return container;
   }
 

core/src/test/java/google/registry/webdriver/DockerWebDriverRule.java

@@ -52,7 +52,8 @@ class DockerWebDriverRule extends ExternalResource {
       url =
           new URL(
               String.format(
-                  "http://localhost:%d/wd/hub",
+                  "http://%s:%d/wd/hub",
+                  container.getContainerIpAddress(),
                   container.getMappedPort(CHROME_DRIVER_SERVICE_PORT)));
     } catch (MalformedURLException e) {
       throw new IllegalArgumentException(e);