Removed Deprecated compute_on_step from Classification

[tanmoyio]

What does this PR do?

Part of #956 - classification

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[codecov]

Codecov Report

Merging #962 (5756a3a) into master (439d205) will increase coverage by 17%.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master   #962     +/-   ##
=======================================
+ Coverage      70%    87%    +17%     
=======================================
  Files         177    177             
  Lines        7509   7509             
=======================================
+ Hits         5290   6533   +1243     
+ Misses       2219    976   -1243