[jdk17u-dev] RFR: 8310683: Refactor StandardCharset/standard.java to use JUnit

[Amos Shi]

Backport of [JDK-8310683](https://bugs.openjdk.org/browse/JDK-8310683)

Testing
- Local: Test passed on `MacOS 14.6.1` on Apple M1 Max
  - `Standard.java`: Test results: passed: 1
- Pipeline: 
- Testing Machine:

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Commit messages:
 - Backport 4e84d4dc514192e4cdf8e2c7c474847832987ab9

Changes: https://git.openjdk.org/jdk17u-dev/pull/2814/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2814&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8310683
  Stats: 128 lines in 1 file changed: 49 ins; 28 del; 51 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/2814.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/2814/head:pull/2814

PR: https://git.openjdk.org/jdk17u-dev/pull/2814