Fix missing deepspeed distributed call

[SeanNaren]

What does this PR do?

Related #9521

After #9044 DeepSpeed was not updated to use the overridden function init_ddp_connection. I've refactored the code such that DeepSpeed handles the necessary initialisation.

As noted by Adrian, #9044 was not included in 1.4.x, so this will be a fix for 1.5

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[kaushikb11]

LGTM!

[codecov]

Codecov Report

Merging #9540 (be965ae) into master (2ec39e2) will increase coverage by 4%.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master   #9540    +/-   ##
=======================================
+ Coverage      89%     93%    +4%     
=======================================
  Files         181     181            
  Lines       15159   15173    +14     
=======================================
+ Hits        13469   14097   +628     
+ Misses       1690    1076   -614     

[ananthsub]

@SeanNaren @tchaton would you be in favor of making deepspeed plug-in inherit from ParallelPlugin directly? Flattening the inheritance structure reduces the risk of bugs like this