Bump test timeout to 4 min

One or two tests, mostly on the powerdns job, are timing out - increase the
timeout while we work through the details.

Change-Id: I2ceaa33f4d49ddf6b2d8b140850c13648a97abde
diff --git a/designate_tempest_plugin/config.py b/designate_tempest_plugin/config.py
index e4e0270..8552015 100644
--- a/designate_tempest_plugin/config.py
+++ b/designate_tempest_plugin/config.py
@@ -38,7 +38,7 @@
                default=1,
                help="Time in seconds between build status checks."),
     cfg.IntOpt('build_timeout',
-               default=120,
+               default=240,
                help="Timeout in seconds to wait for an resource to build."),
     cfg.IntOpt('min_ttl',
                default=1,