RFR: 8358520: Improve lazy computation in BreakIteratorResourceBundle and related classes

[Per Minborg]

This PR proposes to simplify lazy computation related to resource bundles. Previously, some objects were computed lazily using a double-checked locking algorithm. StableValues offers a more robust and succinct solution. 
 
 
This PR passes tier1, tier2, and tier3 on multiple platforms.

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Commit messages:
 - Break out logic in separate methods
 - Revoke the use of immutable collections
 - Fix concurrency issues

Changes: https://git.openjdk.org/jdk/pull/25630/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25630&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8358520
  Stats: 138 lines in 3 files changed: 51 ins; 73 del; 14 mod
  Patch: https://git.openjdk.org/jdk/pull/25630.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25630/head:pull/25630

PR: https://git.openjdk.org/jdk/pull/25630