[fix][prompt] fix ptaas trace

[kasarolzzw]

Change-Id: I1447f2e267c60cdd7a5cdcfedd127cd8eaf8d859

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• This PR title match the format: [<type>][<scope>]: <description>. For example: [fix][backend] flaky fix
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en: fix the issue of ptaas trace prompt_executor span's output content probability loss.
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[codecov]

Codecov Report

❌ Patch coverage is 95.23810% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
backend/modules/prompt/application/openapi.go	92.85%	0 Missing and 1 partial ⚠️

@@           Coverage Diff           @@
##             main     #171   +/-   ##
=======================================
  Coverage   58.20%   58.21%           
=======================================
  Files         511      511           
  Lines       53355    53353    -2     
=======================================
+ Hits        31055    31057    +2     
+ Misses      19919    19917    -2     
+ Partials     2381     2379    -2     

Flag	Coverage Δ
unittests	58.21% <95.23%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...mpt/domain/component/trace/trace_span_convertor.go	77.30% <100.00%> (+0.14%)	⬆️
backend/modules/prompt/application/openapi.go	92.81% <92.85%> (+0.73%)	⬆️

... and 2 files with indirect coverage changes

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