[jdk11u-dev] RFR: 8210406: Refactor java.util.PluggableLocale:i18n shell tests to plain java tests

[Aleksey Shipilev]

Backporting for `11.0.13-oracle` parity.

Additional testing:
 - [x] New tests pass on Linux x86_64
 - [x] `java/util/PluggableLocale` tests pass
 - [x] Eyeballing new test outputs

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Commit messages:
 - Backport 3c2c6bce0249c0674951338afbc7a310e2b36912

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/229/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=229&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8210406
  Stats: 1027 lines in 65 files changed: 274 ins; 625 del; 128 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/229.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/229/head:pull/229

PR: https://git.openjdk.java.net/jdk11u-dev/pull/229