Always start iscsid for nova-compute

Recently iscsid was disabled by default on Ubuntu 18.04 (bionic),
and it may be on Xenial too, see:

https://bugs.launchpad.net/ubuntu/+source/open-iscsi/+bug/1755858

On a local Bionic deployment with Python 3, the lack of iscsid makes
nova-compute fail with an exception when trying to attach a volume:

Invalid input received: Connector doesn't have required information: initiator

Asking for the service to be started even if it is already running should not
hurt, so remove the check for the distribution.

This does not seem to be an issue on CentOS 7 (but Python 2) where
the socket activation of iscsid seems to work, so maybe there is
another way to make this working. Also, the service could be
enabled, not just started.

Change-Id: Ifa995dcf8eb930e959f54e96af6f5fce3eac28ae

lib/nova

@@ -327,10 +327,8 @@ function configure_nova {
                 sudo chown -R $STACK_USER $NOVA_INSTANCES_PATH
             fi
         fi
-        if is_suse; then
-            # iscsid is not started by default
-            start_service iscsid
-        fi
+        # ensure that iscsid is started, even when disabled by default
+        start_service iscsid
     fi
 
     # Rebuild the config file from scratch