remove deprecated sync step argument from WandbLogger

[awaelchli]

What does this PR do?

The sync step argument is deprecated and can be removed now.

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[codecov]

Codecov Report

Merging #8763 (a457477) into master (8473cf4) will decrease coverage by 0%.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master   #8763   +/-   ##
======================================
- Coverage      93%     93%   -0%     
======================================
  Files         169     169           
  Lines       14072   14070    -2     
======================================
- Hits        13041   13039    -2     
  Misses       1031    1031