RFR: 8361717: Refactor Collections.emptyList() in Locale related classes

[Naoto Sato]

Replaced Collections.emptyList() with List.of() as part of refactoring. This was discussed in the context of investigating a CDS-related issue (https://bugs.openjdk.org/browse/JDK-8357281?focusedId=14796714&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-14796714). Although the root cause was ultimately determined to be user error, modernizing the code by using List.of() is still a desirable improvement

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Commit messages:
 - initial commit

Changes: https://git.openjdk.org/jdk/pull/26225/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26225&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8361717
  Stats: 5 lines in 2 files changed: 0 ins; 2 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/26225.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26225/head:pull/26225

PR: https://git.openjdk.org/jdk/pull/26225