test: unmark tests that are no longer flaky

- `test-crypto-domains` was fixed by
joyent/node@2afa3d8a03f1f0798d83dc57abc252bb78b7e591

- All tests under linux appear to be fixed and have not failed recently
on Jenkins

- `test-http-dns-fail` was fixed by the DNS configuration change
mentioned in joyent/node#8056

Fixes #25656
Fixes #25673

Reviewed-By: Alexis Campailla <alexis@janeasystems.com>
PR-URL: https://github.com/joyent/node/pull/25676