Retry juju bootstrap

Retry juju bootstrap for 3 times.

Change-Id: Iafdaf729e950a09c8a13d65545506b1e5166e9d7

roles/microk8s-cloud/tasks/main.yaml

@@ -134,9 +134,13 @@
 
 - name: juju is bootstrapped on microk8s
   command:
-    cmd: juju bootstrap microk8s microk8s
+    cmd: juju bootstrap --config bootstrap-timeout=600 microk8s microk8s
   register: res
-  changed_when: '"already exists" not in res.stderr'
+  retries: 3
+  delay: 10
+  until: >
+    "Bootstrap complete" in res.stderr or
+    "already exists" in res.stderr
   failed_when: '"ERROR" in res.stderr and "already exists" not in res.stderr'
 
 - name: current juju controller is microk8s