tools(foreach): replace relative to absolute paths in build output

[eladb]

this allows running "foreach" from the IDE and have problems
discovered globally.

[Doug-AWS]

Is this change exposed to the user? If so, is there a use case that we should document in the guide?

[mergify]

Thanks so much for taking the time to contribute to the AWS CDK ❤️

We will shortly assign someone to review this pull request and help get it
merged. In the meantime, please take a minute to make sure you follow this
checklist:

• PR title type(scope): text
  • type: fix, feat, refactor go into CHANGELOG, chore is hidden
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• PR Description
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  • Issues: indicate issues fixed via: fixes #xxx or closes #xxx
  • Breaking?: last paragraph: BREAKING CHANGE: <describe what changed + link for details>
• Testing
  • Unit test added. Prefer to add a new test rather than modify existing tests
  • CLI or init templates change? Re-run/add CLI integration tests
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  • README: update module README to describe new features
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