LogsEventDomainContext: fallback to undefined instead of never

[OliverJAsh]

Motivation

This will blow up at runtime, but there's no TypeScript error:

beforeSend: (event, ctx) => {
  // ❌ No TypeScript error
  'foo' in ctx;

This PR fixes the types so we do get a TypeScript error.

Changes

Test instructions

Checklist

• Tested locally
• Tested on staging
• Added unit tests for this change.
• Added e2e/integration tests for this change.

[datadog-datadog-prod-us1]

🎯 Code Coverage
• Patch Coverage: 100.00%
• Total Coverage: 92.63% (+0.00%)

View detailed report

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 8f52631 | Docs | Was this helpful? Give us feedback!}

[thomas-lebeau]

@OliverJAsh, Thank you for your contribution.

Could you accept the license/cla so we can merge your PR.