[feat][backend]: ob get trace refactor

[kidkidkid]

What type of PR is this?

Check the PR title.

• This PR title match the format: [<type>][<scope>]: <description>. For example: [fix][backend] flaky fix
• The description of this PR title is user-oriented and clear enough for others to understand.
• Add documentation if the current PR requires user awareness at the usage level.
• This PR is written in English. PRs not in English will not be reviewed.

(Optional) Translate the PR title into Chinese.

(Optional) More detailed description for this PR(en: English/zh: Chinese).

en:
zh(optional):

(Optional) Which issue(s) this PR fixes:

[codecov]

Codecov Report

❌ Patch coverage is 97.10145% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
backend/modules/observability/infra/rpc/tag/tag.go	0.00%	1 Missing ⚠️
...ckend/modules/observability/infra/tenant/tenant.go	0.00%	1 Missing ⚠️

@@            Coverage Diff             @@
##             main     #276      +/-   ##
==========================================
+ Coverage   69.61%   69.76%   +0.15%     
==========================================
  Files         616      617       +1     
  Lines       58272    58306      +34     
==========================================
+ Hits        40567    40680     +113     
+ Misses      14722    14638      -84     
- Partials     2983     2988       +5     

Flag	Coverage Δ
unittests	69.76% <97.10%> (+0.15%)	⬆️

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

Files with missing lines	Coverage Δ
backend/modules/observability/application/trace.go	72.75% <100.00%> (+0.36%)	⬆️
...es/observability/domain/component/tenant/tenant.go	100.00% <100.00%> (ø)
...bservability/domain/trace/service/trace_service.go	83.81% <100.00%> (ø)
backend/modules/observability/infra/repo/trace.go	85.74% <100.00%> (-0.04%)	⬇️
backend/modules/observability/infra/rpc/tag/tag.go	0.00% <0.00%> (ø)
...ckend/modules/observability/infra/tenant/tenant.go	0.00% <0.00%> (ø)

... and 10 files with indirect coverage changes

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 333e255...b9cc7d6. Read the comment docs.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[CozeLoop]

Aime Review: Identified 1 Must-Fix and several Should-Fix/Suggestions in concurrency and configuration handling. Please see inline comments for details.