Feature request: Enable multi-NIC RDMA support for GPU = 1:2 (CX8) systems in Hybrid-EP / GIN

On the hybrid-ep branch, on B300 systems equipped with CX8 NICs, where each GPU is connected to two RDMA NICs, inter-node communication during training appears to utilize only one NIC per GPU. As a result, the effective RDMA bandwidth per GPU does not scale with the available NIC resources, even though the hardware topology supports concurrent usage of multiple NICs. This behavior is consistently observed on B300 + CX8 platforms across training runs.