RFR: 8378344: Refactor test/jdk/java/net/httpclient/*.java TestNG tests to JUnit [v3]

[Daniel Fuchs]

> TestNG tests directly located in test/jdk/java/net/httpclient/ are refactored to use JUnit.
> 
> This is a mostly mechanical change - though I fixed some compiker warnings along teh way.
> 
> Test only.

Daniel Fuchs has updated the pull request incrementally with one additional commit since the last revision:

  Review feedback: introduce actual/expected

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Changes:
  - all: https://git.openjdk.org/jdk/pull/29850/files
  - new: https://git.openjdk.org/jdk/pull/29850/files/13f03645..a8e95585

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=29850&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=29850&range=01-02

  Stats: 10 lines in 2 files changed: 4 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/29850.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29850/head:pull/29850

PR: https://git.openjdk.org/jdk/pull/29850