Rename Tobiko's three nodes nodesets

devstack is defining the three node focal nodeset
- https://review.opendev.org/#/c/738127
which is blocked because this project also
define the same and zuul complain on conflicting on
name.

Let's rename tobiko nodesets that have (potentially)
conflicting names.

Change-Id: Ic05df3ca6b7f3ebe9413969558ec9a6cd6a0fad8

zuul.d/devstack.yaml

@@ -216,7 +216,7 @@
 - job:
     name: tobiko-devstack-faults-centos-8
     parent: tobiko-devstack-faults
-    nodeset: openstack-three-node-centos-8
+    nodeset: tobiko-three-node-centos-8
     voting: false
 
 
@@ -237,7 +237,7 @@
 - job:
     name: tobiko-devstack-faults-ubuntu-focal
     parent: tobiko-devstack-faults
-    nodeset: openstack-three-node-focal
+    nodeset: tobiko-three-node-focal
     voting: false
     vars:
       devstack_services:

zuul.d/nodes.yaml

@@ -38,7 +38,7 @@
 
 
 - nodeset:
-    name: openstack-three-node-centos-8
+    name: tobiko-three-node-centos-8
     nodes:
       - name: controller
         label: centos-8
@@ -74,7 +74,7 @@
 
 
 - nodeset:
-    name: openstack-three-node-focal
+    name: tobiko-three-node-focal
     nodes:
       - name: controller
         label: ubuntu-focal