Remove hardcoding of rank_zero_only.rank in accelerator connector

[ananthsub]

What does this PR do?

After #6802 this shouldn't be necessary. rank_zero_only populates based on environment variables. With this code around, it risks overriding the cluster environment variables.

Continuation of fixing #6797

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[codecov]

Codecov Report

Merging #6878 (0f0fd67) into master (19e67d1) will decrease coverage by 4%.
The diff coverage is n/a.

❗ Current head 0f0fd67 differs from pull request most recent head aeb3268. Consider uploading reports for the commit aeb3268 to get more accurate results

@@           Coverage Diff           @@
##           master   #6878    +/-   ##
=======================================
- Coverage      91%     87%    -4%     
=======================================
  Files         193     193            
  Lines       12299   12297     -2     
=======================================
- Hits        11252   10703   -549     
- Misses       1047    1594   +547     

[tchaton]

LGTM !