fix: [0km] repair invalid check for ``compose --debug up`` requirement

Since the charm ``cron`` changed, this check require to be updated also.

bin/0km

@@ -953,16 +953,16 @@ vps_install_backup() {
     if [ "$type" == "compose" ]; then
         if ! ssh:run "root@$vps" -- \
              docker exec myc_cron_1 \
-                 cat /etc/cron.d/rsync-backup >/dev/null 2>&1; then
+             grep rsync-backup /etc/crontabs/root >/dev/null 2>&1; then
             ssh:run "root@$vps" -- compose --debug up || {
                 err "Command 'compose --debug up' failed."
                 return 1
             }
             if ! ssh:run "root@$vps" -- \
                  docker exec myc_cron_1 \
-                 cat /etc/cron.d/rsync-backup >/dev/null 2>&1; then
+                 grep rsync-backup /etc/crontabs/root >/dev/null 2>&1; then
                 err "Launched 'compose up' successfully but ${YELLOW}cron${NORMAL} container is not setup as expected."
-                echo "  Was waiting for existence of '/etc/cron.d/rsync-backup' in it." >&2
+                echo "  Was waiting for existence of a line mentionning 'rsync-backup' in '/etc/crontabs/root' in it." >&2
                 return 1
             fi
         fi