[feat][backend] ob trans refactor

[kidkidkid]

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[codecov]

Codecov Report

❌ Patch coverage is 88.46154% with 3 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...bservability/domain/trace/service/trace_service.go	76.92%	2 Missing and 1 partial ⚠️

@@            Coverage Diff             @@
##             main     #298      +/-   ##
==========================================
- Coverage   68.36%   68.36%   -0.01%     
==========================================
  Files         570      570              
  Lines       51562    51569       +7     
==========================================
+ Hits        35250    35254       +4     
- Misses      13573    13580       +7     
+ Partials     2739     2735       -4     

Flag	Coverage Δ
unittests	68.36% <88.46%> (-0.01%)	⬇️

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Files with missing lines	Coverage Δ
...bservability/domain/trace/entity/loop_span/span.go	78.47% <100.00%> (-1.09%)	⬇️
...servability/domain/trace/entity/loop_span/trans.go	73.33% <100.00%> (+0.22%)	⬆️
...bservability/domain/trace/service/trace_service.go	82.04% <76.92%> (+0.11%)	⬆️

... and 4 files with indirect coverage changes

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[CozeLoop]

Aime code review: posted 3 inline comments focusing on concurrency safety with sync.Once, potential redundant filtering in Stat, and processor construction cost in GetTracesAdvanceInfo.