refactor: parametrize tests

[chickenbreeder]

Fixes #1552

Changes

• Parametrized a few tests
• Bumped the rstest version to no longer depend on async-std by default (See: fix: do not depend by default on async-std la10736/rstest#311); this issue only occurred in the context of

#[rstest]
#[tokio::test]

Merge requirement checklist

• CONTRIBUTING guidelines followed
• Unit tests added/updated (if applicable)
• Appropriate CHANGELOG.md files updated for non-trivial, user-facing changes
• Changes in public API reviewed (if applicable)

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: chickenbreeder / name: chickenbreeder (a1e2f3a)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.7%. Comparing base (df412fe) to head (a1e2f3a).

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #3256     +/-   ##
=======================================
- Coverage   80.8%   80.7%   -0.1%     
=======================================
  Files        129     129             
  Lines      23203   23167     -36     
=======================================
- Hits       18750   18714     -36     
  Misses      4453    4453             

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[scottgerring]

I asked Claude to see if there are many others here we could pick up. Not sure how useful this is, but it's probably worth trying to pick out other instances of this pattern we can clean up!

1. opentelemetry-zipkin/src/propagator/mod.rs:464-683
   • B3 propagator tests with extensive test data sets
   • Multiple nested loops for single/multi-header formats
   • Could consolidate 20+ test cases
2. opentelemetry-sdk/src/metrics/internal/exponential_histogram.rs
   - Multiple locations (555-664, 914-1072, 1141-1229)
   - Complex test data structures for bucket calculations
   - 30+ test cases across different test functions
3. opentelemetry-otlp/src/retry.rs:218-495
   - 10+ similar async test functions for retry logic
   - Each tests different scenarios (success, failure, timeout, throttling)
   - Perfect candidate for #[rstest] with #[case] attributes

[scottgerring]

@chickenbreeder let me know when you are ready with this!