Remove warn argument for command/shell

Since ansible-core 2.14 you can't use warn as module argument.

It's being removed to avoid module failure.

Change-Id: I7287d449b8fd0ad970e37aa63b5cb25f88197858

tasks/systemd_mounts.yml

@@ -90,8 +90,6 @@
         systemctl
         {{ systemd_mount_states[item.state] }}
         $(systemd-escape -p --suffix="{{ systemd_mount_suffix }}" "{{ systemd_mount_item }}")
-      args:
-        warn: no
       changed_when: false
       when:
         - item.state is defined