BSW_EFSSecondary: use .efs.cfg configs, fix install_sdp.log symlink conflict
- Use sdp_install.HOSTNAME.efs.cfg (ServerType=p4d_filtered_replica) for EFS
secondary servers so install_sdp.sh creates checkpoints.<suffix> dirs.
- Add rm -f install_sdp.log before install_sdp.sh to clear stale symlink.