Fix icevision task metric names

[ethanwharris]

What does this PR do?

Part of #1244

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[codecov]

Codecov Report

Merging #1252 (e7786c7) into master (536dbfc) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #1252   +/-   ##
=======================================
  Coverage   91.18%   91.19%           
=======================================
  Files         286      286           
  Lines       12790    12793    +3     
=======================================
+ Hits        11662    11666    +4     
+ Misses       1128     1127    -1     

Flag	Coverage Δ
unittests	91.19% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
flash/core/data/utils.py	90.41% <ø> (ø)
flash/core/integrations/icevision/adapter.py	87.91% <ø> (ø)
flash/core/integrations/icevision/wrappers.py	78.26% <100.00%> (+3.26%)	⬆️
flash/text/question_answering/model.py	92.56% <0.00%> (+0.67%)	⬆️

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[krshrimali]

Just a minor comment to pass the stage directly instead of the whole adapter. :) Otherwise, LGTM. thank you so much!