[Cherry-Pick] Make datanode load statslog lazy if SkipBFStatsLog is true

[congqixia]

Cherry-pick from branch 2.2.0
See also #22994
Related to #23477
/kind improvement

[sre-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: congqixia

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[mergify]

@congqixia E2e jenkins job failed, comment /run-cpu-e2e can trigger the job again.

[codecov]

Codecov Report

Merging #23877 (b135c41) into master (38f45c3) will increase coverage by 0.02%.
The diff coverage is 93.82%.

@@            Coverage Diff             @@
##           master   #23877      +/-   ##
==========================================
+ Coverage   79.80%   79.82%   +0.02%     
==========================================
  Files         744      744              
  Lines       97577    97650      +73     
==========================================
+ Hits        77867    77949      +82     
+ Misses      16551    16544       -7     
+ Partials     3159     3157       -2     

Impacted Files	Coverage Δ
internal/datanode/channel_meta.go	94.27% <92.64%> (-0.11%)	⬇️
internal/datanode/data_sync_service.go	80.54% <100.00%> (+0.06%)	⬆️
internal/datanode/segment.go	81.48% <100.00%> (+3.22%)	⬆️

... and 14 files with indirect coverage changes

[jiaoew1991]

/lgtm