Mark `amplificationlimit` QNS test as unsupported

[larseggert]

So the QNS results aren't full of failures. Until we fix #1183.

[martinthomson]

...for our server, that is.

[mxinden]

I am afraid we can not "mark" the test as unsupported, i.e. exit(127). Both client and server do not know the concrete testcase, but instead are told by the Interop Runner that they should execute a transfer. See def testname below.

https://github.com/quic-interop/quic-interop-runner/blob/e15a1e523d915bed008cfc6359f79e1a1458ba6f/testcases.py#L735-L742

An alternative solution would be some heuristic in neqo-client and neqo-server, though at this point, I assume https://github.com/mozilla/neqo/issues/1183 is the easier solution.