️ Repo: add `findUpSyncAny` scenario tests

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Overview

PR #6342 changed deps from find-up to find-up-simple and modified existing tests. This revealed a lack of test coverage for the following scenarios:

• Should call findUpSync in with all config filename args in order
• Should not make extra calls once an item is found
• Should return undefined if no item is found

This guarantees that Mocha behavior is the same as when using find-up. Before, we were able to trust that find-up worked, but now we have (simple) custom code to wrap that, and we should test our custom code.

Additional Info

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