fix(metric engine): label mismatch in metric engine

[v0y4g3r]

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Refer to a related PR or issue link (optional)

• fixes Incorrect label saved when writing metrics with prometheus remote write after flush memtables #3881

What's changed and what's your intention?

This PR fixes the issue where the same primary key gets wrong pk index when dict_builder is frozen. The root cause can be found here.

Performance

This PR has little impaction to the ingestion performance of metric engine.

Checklist

• I have written the necessary rustdoc comments.
• I have added the necessary unit tests and integration tests.
• This PR does not require documentation updates.

[codecov]

Codecov Report

Attention: Patch coverage is 99.08257% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 85.45%. Comparing base (9d12496) to head (34ff396).
Report is 9 commits behind head on main.

❗ Current head 34ff396 differs from pull request most recent head 81afee6. Consider uploading reports for the commit 81afee6 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3927      +/-   ##
==========================================
- Coverage   85.96%   85.45%   -0.51%     
==========================================
  Files         963      967       +4     
  Lines      164580   166172    +1592     
==========================================
+ Hits       141481   142008     +527     
- Misses      23099    24164    +1065     

[fengjiachun]

LGTM

[waynexia]

Fascinating!