I removed the useless option and the need for unwrap from default_config_dir
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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix#20174 (github issue number if applicable).
- [X] These changes do not require tests because they are used at build time.
Source-Repo: https://github.com/servo/servo
Source-Revision: 48ff3965cc2e483a33d457e3ddaf9ad10007c275
(Do not merge) Merge some test crates in their corresponding components
Source-Repo: https://github.com/servo/servo
Source-Revision: a4808a3649e6cb6e579e60b82d9979755643f711