Remove dead code in SmallWorldGraph construction.
Remove dead code in SmallWorldGraph construction.

A for-loop to add left edges was previously never entered because the condition is false at initialization. Adding left edges is unnecessary because the graph is undirected, so it is safe to remove this for-loop.

PiperOrigin-RevId: 330798365

google-research/agent-based-epidemic-sim,google-research/agent-based-epidemic-sim,google-research/agent-based-epidemic-sim