feat(jvb): autoscaler sidecar shutdown hook on finish (#1906)

jvb/rootfs/etc/services.d/jvb/finish

@@ -5,5 +5,5 @@
 # services and shutdown the container.
 
 if [[ $1 -eq 0 ]]; then
-  s6-svscanctl -t /var/run/s6/services
+  /opt/jitsi/shutdown.sh
 fi

jvb/rootfs/opt/jitsi/shutdown.sh

@@ -1,8 +1,11 @@
 #!/usr/bin/with-contenv bash
+
+if [ -n "$AUTOSCALER_URL" ]; then
     # notify the sidecar of imminent shutdown
     PORT=${AUTOSCALER_SIDECAR_PORT:-6000}
     curl -d '{}' -v 0:$PORT/hook/v1/shutdown
     sleep 10
+fi
 
 # shutdown everything
 s6-svscanctl -t /var/run/s6/services