fix(oas): do not drop responses if they have external ref oas2

[chohmann]

Motivation and Context

#17558

Description

• do not drop responses if they have external refs

How Has This Been Tested?

• unit test
• yalc'd into platform-internal and refs.spec.ts tests pass

Screenshot(s)/recordings(s)

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• [x] This PR's code follows as closely as possible the coding style/guidelines of this project.
• [ ] I have added error reporting and followed the error reporting guidelines.
• [ ] I have added event tracking and followed the event tracking guidelines.
• [ ] I have updated any relevant documentation accordingly to reflect this PR's changes.
• [x] I have added automated tests (unit/integration/e2e/other) to cover my changes.
• [x] All new and existing tests pass locally (excluding flaky CI tests).

[stoplight-bot]

:tada: This PR is included in version 5.11.4 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: