Actually make volume extend tests validate

This fixes the previous patch to *actually* wait for the server to
be SSHABLE before continuing the test. Because the volumes tests don't
have full networking and we didn't provide validation resources to
create_server() we weren't *actually* doing the wait for ssh.

Change-Id: I783bbed4bea6137de3afa9a7ecd1a9cd37bb17e8
2 files changed