Don't Use Real Paths In wp-env Tests

[ObliviousHarmony]

Description

We have a report that the wp-env unit tests will fail if your repository directory is not named gutenberg. The problem stems from the many uses of relative paths in config/test/parse-config.js.

Step-by-step reproduction instructions

1. Rename your Gutenberg directory
2. Run npm run test:unit packages/env, they should fail

Screenshots, screen recording, code snippet

No response

Environment info

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Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Yes

[ObliviousHarmony]

Since none of these require reading from any real config file, there's not really a reason to have real paths either. We can replace all of the relative paths in the test file with fake absolute paths. This has the added benefit of simplifying all of the tests too.