chore: upload coverage to codecov

[csuzhangxc]

What problem does this PR solve?

What is changed and how does it work?

Code changes

• Has Go code change
• Has CI related scripts change

Tests

• Unit test
• E2E test
• Manual test
• No code

Side effects

• Breaking backward compatibility
• Other side effects:

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation

Release Notes

Please refer to Release Notes Language Style Guide before writing the release note.

[ti-chi-bot]

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[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Please upload report for BASE (v2@98d923a). Learn more about missing BASE report.

Additional details and impacted files

@@          Coverage Diff          @@
##             v2    #5982   +/-   ##
=====================================
  Coverage      ?   20.00%           
=====================================
  Files         ?      151           
  Lines         ?    10305           
  Branches      ?        0           
=====================================
  Hits          ?     2062           
  Misses        ?     8031           
  Partials      ?      212           

Flag	Coverage Δ
unittest	20.00% <ø> (?)