Prior to this pull request, Next.js would immediately decode all URLs sent to its server (via `path-match`).
This was rarely needed, and Next.js would typically re-encode the incoming request right away (see all the `encodeURIComponent`s removed in PR diff). This adds unnecessary performance overhead.
Long term, this will also help prevent weird encoding edge-cases like #10004, #10022, #11371, et al.
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No new tests are necessary for this change because we've extensively tested these edge cases with existing tests.
One test was updated to reflect that we skip decoding in a 404 scenario.
Let's see if all the existing tests pass!
