8373796: Refactor java/net/httpclient/ThrowingPublishers*.java tests to use JUnit5

[rm-gh-8]

Backporting JDK-8373796: Refactor java/net/httpclient/ThrowingPublishers*.java tests to use JUnit5.

This PR migrates the ThrowingPublishers test family (8 tests + abstract base) from TestNG to JUnit 5, converting data providers to @MethodSource, instance state to static, and the stop-after-first-failure mechanism to a JUnit TestWatcher/BeforeEachCallback extension..

For parity with Oracle JDK.

This PR is not clean because "test/jdk/java/net/httpclient/AbstractThrowingPublishers.java" skips a commit implementing JEP 517 (openjdk/jdk@e8db14f) which is not part of JDK 25. The file has been updated to preserve existing functionality while excluding the JEP 517 changes.

Ran related tests on linux-x64, linux-aarch64, macos-aarch64 and windows-x64:

make test TEST="test/jdk/java/net/httpclient/ThrowingPublishersCustomAfterCancel.java test/jdk/java/net/httpclient/ThrowingPublishersCustomBeforeCancel.java test/jdk/java/net/httpclient/ThrowingPublishersIOAfterCancel.java test/jdk/java/net/httpclient/ThrowingPublishersIOBeforeCancel.java test/jdk/java/net/httpclient/ThrowingPublishersInNextRequest.java test/jdk/java/net/httpclient/ThrowingPublishersInRequest.java test/jdk/java/net/httpclient/ThrowingPublishersInSubscribe.java test/jdk/java/net/httpclient/ThrowingPublishersSanity.java"

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• JDK-8373796 needs maintainer approval

Issue

• JDK-8373796: Refactor java/net/httpclient/ThrowingPublishers*.java tests to use JUnit5 (Sub-task - P4)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk25u-dev.git pull/390/head:pull/390
$ git checkout pull/390

Update a local copy of the PR:
$ git checkout pull/390
$ git pull https://git.openjdk.org/jdk25u-dev.git pull/390/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 390

View PR using the GUI difftool:
$ git pr show -t 390

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk25u-dev/pull/390.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back rm-gh-8! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

[openjdk]

This backport pull request has now been updated with issue from the original commit.

[mlbridge]

Webrevs

• 00: Full (0a24c9f5)