Apply the correct image reference when booting an instance

We seem to be using the Nova's defaults instead. Also verify that the
resulting image type in instance_info is correct.

Depends-On: https://review.opendev.org/c/openstack/ironic/+/827882
Change-Id: Iaba563a2ecbca029889bc6894b2a7f0754d27b88
diff --git a/ironic_tempest_plugin/config.py b/ironic_tempest_plugin/config.py
index de517dc..acf2542 100644
--- a/ironic_tempest_plugin/config.py
+++ b/ironic_tempest_plugin/config.py
@@ -173,6 +173,9 @@
                default='bios',
                choices=['bios', 'uefi'],
                help="The desired boot_mode to be used on testing nodes."),
+    cfg.StrOpt('default_boot_option',
+               # No good default here, we need to actually set it.
+               help="The default boot option the testing nodes are using."),
 ]
 
 BaremetalFeaturesGroup = [