[Bug]: RunInChildContext sometimes fails to checkpoint success when invocation completes

[anthonyting]

Expected Behavior

Success should be checkpointed when runInChildContext is fully awaited and completes.

Actual Behavior

The success isn't checkpointed in some cases

Steps to Reproduce

1. This test is flaky: https://github.com/aws/aws-durable-execution-sdk-js/blob/main/packages/aws-durable-execution-sdk-js-examples/src/examples/run-in-child-context/checkpoint-size-limit/run-in-child-context-checkpoint-size-limit.ts

SDK Version

1.0.0

Node.js Version

22.x

Is this a regression?

No

Last Working Version

No response

Additional Context

The root cause is related to checkpoint API delay.