[fix] for resume training on SLURM multi-node multi-gpu
On SLURM resuming training in a multi-node multi-gpu settings fails, as when `LOCAL_RANK` is undefined `is_globa_rank_zero()` returns true on all processes that run on node 0. In this case `exp_manager.py` https://github.com/NVIDIA/NeMo/blob/f83b2c5524a787be21ffea170850c4b5486eac2b/nemo/utils/exp_manager.py#L446, creates multiple `run_*` folders, and eventually leads to failure (missing files because other processes have moved them already). 

Checking also for `SLURM_PROCID` solves this issue, as the environment variable contains the global rank id.