AsFileDownlodaTest uses Http2TestServer to create HTTP/2 server, and HttpTestServer to create HTTP/3 server. This result in code duplication in the HTTP handler - which implements both Http2TestHandler and HttpTestHandler - resulting in code duplication of the handle() methods.

The test should be updated to use HttpTestServer uniformally, both for HTTP/2 and HTTP/3, which should allow to get rid of the dupliicated code.