Set CONF.image_feature_enabled.api_v1 default to False

Glance v1 APIs are deprecated and v2 APIs are current one,
but CONF.image_feature_enabled.api_v1 now defaults to True,
so CONF.image_feature_enabled.api_v1 must be explicitly set
to False in tempest.conf to avoid using api_v1, which is
annoying. So this is to set CONF.image_feature_enabled.api_v1
default to False.

Change-Id: Iab3a209c744375bf2618afc00a3f7731b62f557e
diff --git a/tempest/config.py b/tempest/config.py
index a8a3bc3..b89f562 100644
--- a/tempest/config.py
+++ b/tempest/config.py
@@ -547,7 +547,7 @@
                                   'test v2 APIs only so this config option '
                                   'will be removed.'),
     cfg.BoolOpt('api_v1',
-                default=True,
+                default=False,
                 help="Is the v1 image API enabled",
                 deprecated_for_removal=True,
                 deprecated_reason='Glance v1 APIs are deprecated and v2 APIs '