[Tuner] Add and fix codecov test in CI

[RattataKing]

• Added coverage git comment report to the test, mainly copied from ci-sharktank.yml
• Polished some env variable

[codecov-commenter]

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Codecov Report

✅ All modified and coverable lines are covered by tests.
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Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2672   +/-   ##
=======================================
  Coverage        ?   77.48%           
=======================================
  Files           ?      264           
  Lines           ?    25251           
  Branches        ?        0           
=======================================
  Hits            ?    19565           
  Misses          ?     5686           
  Partials        ?        0           

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[kuhar]

This doesn't look right. Do you have a link to a successful run that demonstrates this works e2e?

[RattataKing]

This doesn't look right. Do you have a link to a successful run that demonstrates this works e2e?

RattataKing#2
RattataKing#3