CI cleaning

[Borda]

What does this PR do?

Fixes # (issue)

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[codecov]

Codecov Report

Merging #4941 (40a816e) into master (a941f96) will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master   #4941   +/-   ##
======================================
  Coverage      93%     93%           
======================================
  Files         124     124           
  Lines        9320    9320           
======================================
  Hits         8640    8640           
  Misses        680     680           

[Borda]

his we can probably drop the relative path to root for Horovod... :]

[tchaton]

Awesome work there !