<i18n dev> RFR: 8342582: user.region for formatting number no longer works for 21.0.5 [v3]

[Naoto Sato]

> This is a regression caused by the fix to [JDK-8321206](https://bugs.openjdk.org/browse/JDK-8321206), where the default locale with `user.region` creation is inadvertently broken. Fix is to restore the user.region override within StaticProperty initialization.

Naoto Sato has updated the pull request incrementally with one additional commit since the last revision:

  Corrected wrong assumption in the test

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Changes:
  - all: https://git.openjdk.org/jdk/pull/21645/files
  - new: https://git.openjdk.org/jdk/pull/21645/files/2e5f2e0b..2ce3643c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21645&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21645&range=01-02

  Stats: 2 lines in 1 file changed: 0 ins; 1 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/21645.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21645/head:pull/21645

PR: https://git.openjdk.org/jdk/pull/21645