Use less resources in sceanrio gate job

There are many failures now due to the timeout for instances creation
and so let's try to use less resources - m1.tiny flavor and 1GB vol.

Change-Id: I2f56112013033824d46f6e460a52efeffda5548a

etc/scenario/gate/fake.yaml.mako

@@ -11,7 +11,7 @@ clusters:
           - datanode
           - tasktracker
         volumes_per_node: 2
-        volumes_size: 2
+        volumes_size: 1
         auto_security_group: true
       - name: worker
         flavor: ${ci_flavor_id}
@@ -19,7 +19,7 @@ clusters:
           - datanode
           - jobtracker
         volumes_per_node: 2
-        volumes_size: 2
+        volumes_size: 1
         auto_security_group: true
     cluster_template:
       name: fake01

tools/gate/scenario/post_test_hook.sh

@@ -42,7 +42,7 @@ network_type: ${NETWORK}
 network_private_name: ${PRIVATE_NETWORK_NAME}
 network_public_name: ${PUBLIC_NETWORK_NAME}
 fake_plugin_image: ${SAHARA_FAKE_PLUGIN_IMAGE_NAME}
-ci_flavor_id: '2'
+ci_flavor_id: '1'
 cluster_name: fake-cluster
 EOF