fix bug in conditional script

bin/vernemq.sh

@@ -122,12 +122,12 @@ siguser1_handler() {
 # SIGTERM-handler
 sigterm_handler() {
     echo "Stopping VerneMQ Pod... VerneMQ@${IP_ADDRESS} "
-    #if [ $pid -ne 0 ]; then
+    if [[ $pid -ne 0 ]]; then
         echo "Leaving cluster..."
         # this will stop the VerneMQ process
         vmq-admin cluster leave node=VerneMQ@$IP_ADDRESS -k > /dev/null
         wait "$pid"
-    #fi
+    fi
     exit 143; # 128 + 15 -- SIGTERM
 }