[jdk17u] RFR: 8305900: Use loopback IP addresses in security policy files of httpclient tests

[Goetz Lindenmaier]

I backport this to fix testing issues with ConnectionReueseTest.java that showed after backporting https://bugs.openjdk.org/browse/JDK-8305906.

Jaikiran proposes to do a local fix, but I think backporting this test-only change keeps the test suite better up-to-date. Also later similar issues will be avoided.

Some simple adaptions were needed:

test/jdk/java/net/httpclient/AsFileDownloadTest.java
Trivial resolve.

test/jdk/java/net/httpclient/httpclient-localaddr-security.policy
File not in 17. Skipped.

test/jdk/java/net/httpclient/lib/jdk/httpclient/test/lib/common/HttpServerAdapters.java
test/jdk/java/net/httpclient/lib/jdk/httpclient/test/lib/http2/Http2TestServer.java
Trivial resolve, file in other loction.

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Commit messages:
 - Backport 646b666a265c4de961b8ba3f9e4e8c9231be8a6f

Changes: https://git.openjdk.org/jdk17u/pull/390/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u&pr=390&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8305900
  Stats: 429 lines in 32 files changed: 193 ins; 38 del; 198 mod
  Patch: https://git.openjdk.org/jdk17u/pull/390.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u.git pull/390/head:pull/390

PR: https://git.openjdk.org/jdk17u/pull/390