While some of these tests are for DoT which doesn't require nghttp2,
the server configs won't allow the server to start without nghttp2
support during compile time.
It might be possible to split these tests into DoT and DoH and only
require nghttp2 for DoH tests, but since almost all of our CI jobs are
compiled with nghttp2, we wouldn't gain a lot of coverage, so it's
probably not worth the effort.