Multi-node: Streamline multi-node-known-hosts

We're now evaluating the condition whether or not to run this role
at the playbook level instead since there are different roles using
this same condition.

Change-Id: I99738c7e98133838f989ed369a09ecb6a7b64054

roles/multi-node-known-hosts/tasks/main.yaml

@@ -1,3 +1,9 @@
-- name: Setup known_hosts for cross-node SSH'ing when we have more than 1 host
-  include: setup-multinode-known-hosts.yaml
-  when: hostvars|length > 1
+- name: Get known_hosts facts
+  generate_all_known_hosts:
+    hostvars: "{{ hostvars }}"
+
+- name: add known_host record for every public key of every other ip, hostname
+  known_hosts:
+    name: "{{ item.name }}"
+    key: "{{ item.key }}"
+  with_items: "{{ all_known_hosts }}"

roles/multi-node-known-hosts/tasks/setup-multinode-known-hosts.yaml

@@ -1,10 +0,0 @@
-- name: Get known_hosts facts
-  generate_all_known_hosts:
-    hostvars: "{{ hostvars }}"
-
-- name: add known_host record for every public key of every other ip, hostname
-  known_hosts:
-    name: "{{ item.name }}"
-    key: "{{ item.key }}"
-  with_items:
-    "{{ all_known_hosts }}"