RFR: 8378164: test/jdk/java/net/httpclient/http3/*.java: convert tests that use ITestContext to JUnit [v2]

[Daniel Fuchs]

> Similar to https://github.com/openjdk/jdk/pull/29786 - this time with HTTP/3 tests.

Daniel Fuchs has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:

 - Merge branch 'master' into ITestContext-http3-8378164
 - 8378164: test/jdk/java/net/httpclient/http3/*.java: convert tests that use ITestContext to JUnit

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/29824/files
  - new: https://git.openjdk.org/jdk/pull/29824/files/f0aba189..31ad86bf

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=29824&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=29824&range=00-01

  Stats: 3384 lines in 83 files changed: 746 ins; 2479 del; 159 mod
  Patch: https://git.openjdk.org/jdk/pull/29824.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29824/head:pull/29824

PR: https://git.openjdk.org/jdk/pull/29824