feat(sampler-composite): rename createComposableTraceIDRatioBasedSampler to createComposableProbabilitySampler

[ravitheja4531-cell]

Summary

• Renames createComposableTraceIDRatioBasedSampler → createComposableProbabilitySampler in @opentelemetry/sampler-composite per issue rename createComposableTraceIDRatioBasedSampler to createComposableProbabilitySampler #6540
• Renames internal class ComposableTraceIDRatioBasedSampler → ComposableProbabilitySampler
• Replaces src/traceidratio.ts with src/probability.ts and test/traceidratio.test.ts with test/probability.test.ts
• Updates README.md and experimental/CHANGELOG.md

Closes #6540

Test plan

• All 69 tests pass in experimental/packages/sampler-composite
• New probability.test.ts covers description strings and sampling ratios

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.75%. Comparing base (1cf5ef3) to head (a7b0634).
⚠️ Report is 11 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6564      +/-   ##
==========================================
+ Coverage   95.74%   95.75%   +0.01%     
==========================================
  Files         371      375       +4     
  Lines       12514    12725     +211     
  Branches     2962     3013      +51     
==========================================
+ Hits        11981    12185     +204     
- Misses        533      540       +7     

Files with missing lines	Coverage Δ
...ntal/packages/sampler-composite/src/probability.ts	95.45% <100.00%> (ø)

... and 12 files with indirect coverage changes

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[maryliag]

Hey @ravitheja4531-cell I just noticed this is your first contribution in this repo! Welcome and thank you for contributing! 😄

There is just one small suggestion I made that you can "commit suggestion" and we should be able to approve/merge after that!

[ravitheja4531-cell]

@maryliag Thanks for the guidance .Really appreciate that . Commited the changes as suggested.

[pichlermarc]

thank you for working on this 🙌
looks good overall, changelog entry should go into the breaking changes section though :)