RFR: 8355522: Remove the `java.locale.useOldISOCodes` system property [v4]

[Joe Wang]

On Wed, 23 Jul 2025 17:39:12 GMT, Naoto Sato <naoto at openjdk.org> wrote:

>> This PR removes the system property deprecated in JDK 25. If the property is specified at runtime, a warning will be emitted at startup to inform the user that the value is ignored. A corresponding CSR has been drafted as well
>
> Naoto Sato has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Further wording refinement

Marked as reviewed by joehw (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/26419#pullrequestreview-3245786867