Lookup socket instead of hardcoding in run_react_infer.sh

[tobrun]

Currently NCCL_SOCKET_IFNAME and GLOO_SOCKET_IFNAME are hardcoded while it could be resolved with a simple lookup.

This results in errors:

• no socket interface found
• Unable to find address for: eth0

[AgentAashik]

don’t hardcode eth0 — either set the variables to the right interface name on your machine or let the libraries auto-detect.