calico: fix NetworkManager check (#7169)

Previous check for presence of NM assumed "systemctl show
NetworkManager" would exit with a nonzero status code, which seems not
the case anymore with recent Flatcar Container Linux.

This new check also checks the activeness of network manager, as
`is-active` implies presence.

Signed-off-by Jorik Jonker <jorik@kippendief.biz>

roles/network_plugin/calico/tasks/install.yml

@@ -8,7 +8,7 @@
 
 - name: Calico | Check if host has NetworkManager
   # noqa 303 Should we use service_facts for this?
-  command: systemctl show NetworkManager
+  command: systemctl is-active --quiet NetworkManager.service
   register: nm_check
   failed_when: false
   changed_when: false