Add ability to set reauthentication_auth_method option

To allow heat to reauthenticate using trusts for long running tasks
this option is needed to be set to 'trusts'.

Change-Id: I48c36487aee5cde5fd3cf139766038fecd7e3f28
Related-Prod: https://mirantis.jira.com/browse/PROD-27017
diff --git a/tests/pillar/server_plugin_dirs.sls b/tests/pillar/server_plugin_dirs.sls
index d96fac7..6f83cdc 100644
--- a/tests/pillar/server_plugin_dirs.sls
+++ b/tests/pillar/server_plugin_dirs.sls
@@ -3,6 +3,7 @@
     enabled: true
     region: RegionOne
     version: ocata
+    reauthentication_auth_method: trusts
     stack_domain_admin:
       name: heat_domain_admin
       password: password