Fix systemd service unit

EnvironmentFile was statically set when it should've been pointing to
/etc/default/vault
for Debian and
/etc/sysconfig/vault
for CentOS/EL.

vault/files/vault.service

@@ -4,7 +4,7 @@ Requires=network-online.target
 After=network-online.target{% if config.storage and config.storage.type == "consul" %} consul.service{% endif %}
 
 [Service]
-EnvironmentFile=-/etc/sysconfig/vault
+EnvironmentFile=-/etc/{% if grains['os_family'] == 'Debian' %}default{% else %}sysconfig{% endif %}/vault
 User={{ user }}
 Group={{ group }}
 ExecStart=/usr/local/bin/vault server {% if config.dev_mode %}-dev{% else %}-config="/etc/vault.d/config.hcl"{% endif %}