Refactor the only test in `java/util/prefs` that uses TestNG to use JUnit instead.
------------- Commit messages: - 8380198: Convert java/util/prefs/PrefsSpiTest.java to JUnit Changes: https://git.openjdk.org/jdk/pull/30268/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=30268&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8380198 Stats: 26 lines in 1 file changed: 7 ins; 6 del; 13 mod Patch: https://git.openjdk.org/jdk/pull/30268.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/30268/head:pull/30268 PR: https://git.openjdk.org/jdk/pull/30268
