Don't use hardcoded flavors in tests

Use config values instead.

Change-Id: I5755ddc628e08a4336debef4022bebf1542b0200
diff --git a/functional/test_cancel_update.py b/functional/test_cancel_update.py
index f6ddc07..bfeeda6 100644
--- a/functional/test_cancel_update.py
+++ b/functional/test_cancel_update.py
@@ -53,7 +53,7 @@
 
         stack_identifier = self.stack_create(template=self.template,
                                              parameters=parameters)
-        parameters['InstanceType'] = 'm1.large'
+        parameters['InstanceType'] = self.conf.instance_type
         self.update_stack(stack_identifier, self.template,
                           parameters=parameters,
                           expected_status='UPDATE_IN_PROGRESS')
diff --git a/functional/test_conditional_exposure.py b/functional/test_conditional_exposure.py
index bf6cc47..69cff79 100644
--- a/functional/test_conditional_exposure.py
+++ b/functional/test_conditional_exposure.py
@@ -23,13 +23,16 @@
     unavailable_service = 'Sahara'
     unavailable_template = """
 heat_template_version: 2015-10-15
+parameters:
+  instance_type:
+    type: string
 resources:
   not_available:
     type: OS::Sahara::NodeGroupTemplate
     properties:
       plugin_name: fake
       hadoop_version: 0.1
-      flavor: m1.large
+      flavor: {get_param: instance_type}
       node_processes: []
 """
 
@@ -56,9 +59,11 @@
 
     def test_unavailable_resources_not_created(self):
         stack_name = self._stack_rand_name()
+        parameters = {'instance_type': self.conf.minimal_instance_type}
         ex = self.assertRaises(exc.HTTPBadRequest,
                                self.client.stacks.create,
                                stack_name=stack_name,
+                               parameters=parameters,
                                template=self.unavailable_template)
         self.assertIn('ResourceTypeUnavailable', ex.message)
         self.assertIn('OS::Sahara::NodeGroupTemplate', ex.message)