Fix nodesets for tricircle multi-region job

After automatical migration of tricircle jobs, tricircle
multi-region job fails because the seconde node is not
correctly running. This patch modifies the tricircle job
definition to inherit from legacy-dsvm-base-multinode and
also configure nodesets.

Change-Id: I40aa62f48fa19299dcb0a63c7325fc895215d7f6

playbooks/legacy/tricircle-dsvm-multiregion/run.yaml

@@ -1,4 +1,4 @@
-- hosts: all
+- hosts: primary
   name: Autoconverted job legacy-tricircle-dsvm-multiregion from old job gate-tricircle-dsvm-multiregion-ubuntu-xenial
   tasks:
 

zuul.d/zuul-legacy-jobs.yaml

@@ -14344,7 +14344,7 @@
 
 - job:
     name: legacy-tricircle-dsvm-multiregion
-    parent: legacy-dsvm-base
+    parent: legacy-dsvm-base-multinode
     run: playbooks/legacy/tricircle-dsvm-multiregion/run
     post-run: playbooks/legacy/tricircle-dsvm-multiregion/post
     timeout: 7800
@@ -14352,6 +14352,7 @@
       - openstack-infra/devstack-gate
       - openstack/networking-sfc
       - openstack/tricircle
+    nodeset: legacy-ubuntu-xenial-2-node
 
 - job:
     name: legacy-trio2o-dsvm-functional