[jdk17u-dev] RFR: 8317372: Refactor some NumberFormat tests to use JUnit

[Andrew Lu]

I backport this for parity with 17.0.13-oracle.

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

Commit messages:
 - Backport 9622de2aa89923b8444df093ae1c596bc336f14f

Changes: https://git.openjdk.org/jdk17u-dev/pull/2628/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2628&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8317372
  Stats: 948 lines in 9 files changed: 395 ins; 195 del; 358 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/2628.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/2628/head:pull/2628

PR: https://git.openjdk.org/jdk17u-dev/pull/2628