Use build_timeout & build_interval from heat config.

These are used by the wait_for method.

Change-Id: I61b8b2485b8a2a82fb6b482b49d1db3c624d7904
diff --git a/tempest/api/orchestration/base.py b/tempest/api/orchestration/base.py
index fa8190a..0e50ac3 100644
--- a/tempest/api/orchestration/base.py
+++ b/tempest/api/orchestration/base.py
@@ -33,6 +33,8 @@
         cls.orchestration_cfg = os.config.orchestration
         if not cls.orchestration_cfg.heat_available:
             raise cls.skipException("Heat support is required")
+        cls.build_timeout = cls.orchestration_cfg.build_timeout
+        cls.build_interval = cls.orchestration_cfg.build_interval
 
         cls.os = os
         cls.orchestration_client = os.orchestration_client