test: make durable wait races deterministic

[jeremydixon22]

Summary

• replace the AWS test's 20 ms wall-clock timeout with a fixture-controlled due wait so the event/timeout race remains real and deterministic
• assert the local runtime's durable wait.registered history event instead of requiring a poll to observe a brief intermediate status
• preserve the product assertions while removing two timing failures observed under concurrent CI load

Verification

• both focused tests passed 20 consecutive runs apiece
• complete Vyral.Tests.Aws project: 38 passed, 36 live tests skipped
• complete Vyral.Tests.Local project: 327 passed, 1 optional live test skipped
• both changed files pass scoped dotnet format --verify-no-changes
• scripts/verify-public-export.sh --allow-dirty
• git diff --check

Public-information declaration

Yes. This change contains public test-fixture code and regenerated public-export evidence only. It includes no credentials, internal planning discussion, maturity promotion, or publication action.