<i18n dev> RFR: JDK-8317372: Refactor some NumberFormat tests to use JUnit [v3]

[Justin Lu]

> Please review this PR which refactors a number of tests under `test/text/NumberFormat` to use JUnit.
> 
> During the switch to JUnit, the tests had the following updates (to improve readability)
> - separate the test data generation from the actual execution of the test
> - create distinct test methods so that all the tests aren't just run under one big method (e.g. main)

Justin Lu has updated the pull request incrementally with one additional commit since the last revision:

  Swap grouping and decimal separator

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Changes:
  - all: https://git.openjdk.org/jdk/pull/16035/files
  - new: https://git.openjdk.org/jdk/pull/16035/files/22d7e1a6..7c62b652

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16035&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16035&range=01-02

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/16035.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16035/head:pull/16035

PR: https://git.openjdk.org/jdk/pull/16035