Make configure-agent-env.service idempotent.

When the configure-agent-env.service service is restarted it will fail
when it tries to create the directory /etc/kubernetes, leaving the
system 'degraded' from systemd's perspective, this change adds the '-p'
flag to mkdir to fail silently if the directory already exists.

Change-Id: I79c3beebd790f2e7c787cf1c34be3c5a26cca2d0
Related-Bug: #1982872
(cherry picked from commit 64570c2)

Author: freyes

magnum/drivers/k8s_fedora_coreos_v1/templates/fcct-config.yaml

@@ -124,7 +124,7 @@ storage:
           done
 
           /usr/bin/update-ca-trust
-          mkdir /etc/kubernetes/
+          mkdir -p /etc/kubernetes/
           cp /etc/pki/tls/certs/ca-bundle.crt /etc/kubernetes/ca-bundle.crt
 
           HTTP_PROXY="__HTTP_PROXY__"