fix NETBIRD_SIGNAL_PORT not working with custom port (#1143) (#1145)

Use NETBIRD_SIGNAL_PORT variable instead of the static port for signal
container in the docker-compose template to make setting of custom
signal port working

Signed-off-by: Fabio Fantoni <fabio.fantoni@m2r.biz>

infrastructure_files/docker-compose.yml.tmpl

@@ -36,7 +36,7 @@ services:
     volumes:
       - $SIGNAL_VOLUMENAME:/var/lib/netbird
     ports:
-      - 10000:80
+      - $NETBIRD_SIGNAL_PORT:80
   #      # port and command for Let's Encrypt validation
   #      - 443:443
   #    command: ["--letsencrypt-domain", "$NETBIRD_LETSENCRYPT_DOMAIN", "--log-file", "console"]