RFR: 8352431: java/net/httpclient/EmptyAuthenticate.java uses "localhost"

[Volkan Yazici]

Overhauls `EmptyAuthenticate` to

- Test all supported HTTP versions (i.e., HTTP/1.1 and HTTP/2)
- Test both clear-text and SSL
- Use `HttpServerAdapters.HttpTestServer::create` to avoid host-related problems

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Commit messages:
 - Overhaul `EmptyAuthenticate`

Changes: https://git.openjdk.org/jdk/pull/24542/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24542&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8352431
  Stats: 121 lines in 1 file changed: 82 ins; 19 del; 20 mod
  Patch: https://git.openjdk.org/jdk/pull/24542.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24542/head:pull/24542

PR: https://git.openjdk.org/jdk/pull/24542