sandbox: drop redundant sync after multi-node port-file write (#1458)

Signed-off-by: gwarmstrong <gwarmstrong@users.noreply.github.com>
Co-authored-by: gwarmstrong <gwarmstrong@users.noreply.github.com>

Author: gwarmstrong

dockerfiles/sandbox/start-with-nginx.sh

@@ -562,7 +562,6 @@ if [ "$NODE_COUNT" -gt 1 ]; then
         echo "${i}:${ACTUAL_WORKER_PORTS[$((i-1))]}" >> "$PORTS_FILE"
     done
     echo "PORT_REPORT_COMPLETE" >> "$PORTS_FILE"
-    sync
     echo "[$_H] Port assignments written to $PORTS_FILE"
 fi