The expected behavior is that the connection to the old primary will close and that Vitess will try to reconnect to the new primary.

To ensure that the expected behavior occurs when using AWS/Aurora you will need to set the vttablet flag -pool_hostname_resolve_interval to something other than the default. This is because the default is 0. When this flag is set to the default, Vitess will never re-resolve the AWS/Aurora DNS name.