[sampler-aws-xray] flaky tests

[pichlermarc]

In recent days we've seen a recent uptick in flaky tests in @opentelemetry/sampler-aws-xray as some of them are depending on timing, this is blocking PRs (releases, dependency updates), should be addressed ASAP.

Example: https://github.com/open-telemetry/opentelemetry-js-contrib/actions/runs/22177072713/job/64129205366?pr=3393#step:10:4151

[pichlermarc]

Marking this as P1 as it has been holding back required checks on PRs for security updates for dependencies of components. These have not been critical ones yet but it's causing churn on github issues.

cc @jj22ee, @yiyuan-he - component owners

[yiyuan-he]

Thanks for flagging this @pichlermarc! I'll take a look at #3396 and #3397 and get reviews in shortly.