Add more roles to designate formulas

Provide roles:
pool_manager
worker
agent

The idea was proposed by Aleš Komárek:
https://gerrit.mcp.mirantis.net/6723

Make adjustments to designate.conf.Debian to be able
to take into account pool_manager changes in
reclass model.

Provide default roles description in pillars for tests.

Change-Id: I214d8db39365648b5ef9348b52edd839327ca197
Related-PROD: https://mirantis.jira.com/browse/PROD-14396
diff --git a/tests/pillar/designate_mitaka.sls b/tests/pillar/designate_mitaka.sls
index 8543c76..e0e3f67 100644
--- a/tests/pillar/designate_mitaka.sls
+++ b/tests/pillar/designate_mitaka.sls
@@ -1,4 +1,6 @@
 designate:
+  pool_manager:
+    enabled: true
   server:
     enabled: true
     region: RegionOne