RFR: 8373798: Refactor java/math tests to use JUnit

[Raffaello Giulietti]

Replace testng framework with junit

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Commit messages:
 - 8373798: Refactor java/math tests to use JUnit

Changes: https://git.openjdk.org/jdk/pull/28848/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28848&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8373798
  Stats: 124 lines in 2 files changed: 43 ins; 11 del; 70 mod
  Patch: https://git.openjdk.org/jdk/pull/28848.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28848/head:pull/28848

PR: https://git.openjdk.org/jdk/pull/28848