Use ZUUL_TEST_ROOT in launcher

With this, the ansible launch server will automatically honor the
test root when it creates its tempdirs.

Change-Id: I4794c59cf7db63a992415a8933259bd0a2e4af54
diff --git a/tests/base.py b/tests/base.py
index b745cc2..649de26 100755
--- a/tests/base.py
+++ b/tests/base.py
@@ -1273,6 +1273,7 @@
 
         self.launch_server = RecordingLaunchServer(
             self.config, self.connections,
+            jobdir_root=self.test_root,
             _run_ansible=self.run_ansible,
             _test_root=self.test_root)
         self.launch_server.start()