Add to tempest conf new  variable

Reguister new variable barbican_integration_enabled in
tempest config -> compute_feature_enabled section

Related-prod: PROD-22506

Change-Id: I419b055e5224f498f3c4082bfd88de25a7354ff4
(cherry picked from commit e7a4336bd28d304e4001a3d9e17da4aa3eabacdc)
diff --git a/tempest/config.py b/tempest/config.py
index a53989f..7d50c2d 100644
--- a/tempest/config.py
+++ b/tempest/config.py
@@ -494,6 +494,9 @@
                 help='Does the test environment support attaching a volume to '
                      'more than one instance? This depends on hypervisor and '
                      'volume backend/type and compute API version 2.60.'),
+    cfg.BoolOpt('barbican_integration_enabled',
+                default=False,
+                help='Does the test environment support Barbican integration'),
 ]