chore: add UT for config pkg; mirror fix

[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.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 92.45283% with 4 lines in your changes missing coverage. Please review.

Project coverage is 23.69%. Comparing base (3a93897) to head (a53ccb2).

Additional details and impacted files

@@              Coverage Diff               @@
##           feature/v2    #6006      +/-   ##
==============================================
+ Coverage       21.14%   23.69%   +2.54%     
==============================================
  Files             152      152              
  Lines           10379    10401      +22     
==============================================
+ Hits             2195     2464     +269     
+ Misses           7972     7721     -251     
- Partials          212      216       +4     

Flag	Coverage Δ
unittest	23.69% <92.45%> (+2.54%)	⬆️

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