enhance: add log for partition stats( #30376)

[MrPresent-Han]

related: #30376

[codecov]

Codecov Report

Attention: Patch coverage is 96.42857% with 1 line in your changes missing coverage. Please review.

Project coverage is 70.52%. Comparing base (a642a26) to head (bad763f).
Report is 21 commits behind head on master.

Files	Patch %	Lines
internal/querynodev2/delegator/delegator.go	87.50%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           master   #35219       +/-   ##
===========================================
- Coverage   81.54%   70.52%   -11.02%     
===========================================
  Files        1188     1193        +5     
  Lines      142311   142056      -255     
===========================================
- Hits       116047   100186    -15861     
- Misses      21935    37523    +15588     
- Partials     4329     4347       +18     

Files	Coverage Δ
internal/querycoordv2/checkers/leader_checker.go	96.37% <100.00%> (+0.22%)	⬆️
internal/querycoordv2/meta/target_manager.go	88.80% <100.00%> (+0.20%)	⬆️
internal/querynodev2/delegator/delegator.go	87.02% <87.50%> (+0.15%)	⬆️

... and 317 files with indirect coverage changes

[congqixia]

/lgtm

[sre-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: congqixia, MrPresent-Han

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• internal/querycoordv2/checkers/OWNERS [congqixia]
• internal/querycoordv2/meta/OWNERS [congqixia]
• internal/querynodev2/delegator/OWNERS [congqixia]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment