[fix] Fix multi-node DDP launch by using local rank instead of global rank for main process

[ananthsub]

What does this PR do?

Fixes #7060

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[codecov]

Codecov Report

Merging #7061 (8c2d4ea) into master (832a03a) will decrease coverage by 5%.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master   #7061    +/-   ##
=======================================
- Coverage      92%     87%    -5%     
=======================================
  Files         196     196            
  Lines       12571   12571            
=======================================
- Hits        11594   10942   -652     
- Misses        977    1629   +652