refactor(profiling): use libdd-profiling's ThinStr

[morrisonlevi]

Description

This replaces the ThinStr defined in this module with the one that is in libdd-profiling instead. Note that the one in libdd-profiling was a copy + refactor of this one, which is why the migration is so easy.

Reviewer checklist

• Test coverage seems ok.
• Appropriate labels assigned.

[datadog-official]

⚠️ Tests

✨ Fix all issues with Cursor

⚠️ Warnings

🧪 1 Test failed

testSearchPhpBinaries from integration.DDTrace\Tests\Integration\PHPInstallerTest (Datadog) (Fix with Cursor)

Risky Test
phpvfscomposer://tests/vendor/phpunit/phpunit/phpunit:97

ℹ️ Info

❄️ No new flaky tests detected

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 0f89690 | Docs | Datadog PR Page | Was this helpful? Give us feedback!}

[pr-commenter]

Benchmarks [ profiler ]

Benchmark execution time: 2026-02-10 17:34:39

Comparing candidate commit 30e16e1 in PR branch levi/thin-str-cleanup with baseline commit cec436d in branch master.

Found 2 performance improvements and 0 performance regressions! Performance is the same for 26 metrics, 8 unstable metrics.

scenario:walk_stack/50

• 🟩 wall_time [-792.848ns; -779.772ns] or [-4.879%; -4.798%]

scenario:walk_stack/99

• 🟩 wall_time [-685.043ns; -676.939ns] or [-4.245%; -4.195%]

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 62.21%. Comparing base (cec436d) to head (30e16e1).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3631      +/-   ##
==========================================
+ Coverage   62.20%   62.21%   +0.01%     
==========================================
  Files         141      141              
  Lines       13387    13387              
  Branches     1753     1753              
==========================================
+ Hits         8327     8329       +2     
+ Misses       4263     4260       -3     
- Partials      797      798       +1     

see 1 file with indirect coverage changes

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