[ROCm] fix build failure when nccl is enabled (#19900)
Building onnxruntime ROCm EP with --enable_nccl --use_mpi fails due to
inclusion of MOE source files but MOE is not supported. The error
observed is
`error: contrib_ops/rocm/moe/ft_moe/moe_kernel.h: No such file or
directory`
The fix is to exclude collective/sharded_moe.* files when nccl is
requested.
