ngtcp2: overwrite rate-limits defaults

ngtcp2: overwrite rate-limits defaults

In pytests test_08 with the Caddy server, the new rate-limiting in
ngtcp2 did close the connection because it found "too many" stream data
packet repeats.

It is unclear if this is some Caddy issue or if the ngtcp2 implementaton
is wrong. Or if curl can do anything here.

Reported as https://github.com/ngtcp2/ngtcp2/issues/1850

This PR overwrites the ratelimit defaults in ngtcp2 with ten times
increased values. This makes the errors disappear on macOS.

Enable test_08_04/05 in CI again to see if there are any issues
to be found there. (We had those disabled before having parallel
pytests.)

Closes #19274