Reenable skipped tests for netlify dev and middleware work

[nickytonline]

Some tests were skipped as they only ran locally but not in CI. Investigate why the skipped tests weren't able to run successfully in CI/CD.

See #1831

[sarahetter]

#1953 - closing this issue, but ensure this work is done in this ticket

[MarcL]

Hey @nickytonline!

Closing this as we've got better test coverage on the v5 runtime now. 💪🏻

The v4 runtime is now in the maintenance support phase, with no new features being added. Occasional bug fixes and security patches will be applied when needed.

Thanks!