Unhardcode instance_build_timeout option

This patch allows to configure instance_build_timeout option that
defines maximum time in seconds that an instance can take to build.

Change-Id: Ia589aa368a87f02df3955697b19bcafe6e6390d7
diff --git a/tests/pillar/control_cluster.sls b/tests/pillar/control_cluster.sls
index 397d659..ab37b5f 100644
--- a/tests/pillar/control_cluster.sls
+++ b/tests/pillar/control_cluster.sls
@@ -12,6 +12,7 @@
     ram_allocation_ratio: 1.5
     disk_allocation_ratio: 1.0
     workers: 8
+    instance_build_timeout: 600
     bind:
       private_address: 127.0.0.1
       public_address: 127.0.0.1