<i18n dev> RFR: 8312416: Tests in Locale should have more descriptive names

[Justin Lu]

Please review this change which renames tests for Locale from `bugNNNNNNN.java` to something more descriptive.

In addition to the name changes, accompanying copyright year, name usage within the test, and other minor changes were included. The test `bug4123285.java` was also removed, as it was never actually ran and java.applet.Applet is deprecated and marked for removal.

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Commit messages:
 - Copyright years, import cleanup, name within file, etc.
 - Rename files and remove unusued test files

Changes: https://git.openjdk.org/jdk/pull/15032/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15032&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8312416
  Stats: 265 lines in 16 files changed: 93 ins; 138 del; 34 mod
  Patch: https://git.openjdk.org/jdk/pull/15032.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15032/head:pull/15032

PR: https://git.openjdk.org/jdk/pull/15032