<i18n dev> [jdk19] RFR: 8289252: Recommend Locale.of() method instead of the constructor

[Naoto Sato]

This is a leftover documentation fix to the deprecation of `Locale` constructors. `Locale.Builder` class had some texts that suggested using one of those constructors, which need to be replaced with a `Locale.of()` method. A corresponding CSR has also been drafted.

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Commit messages:
 - 8289252: Recommend Locale.of() method instead of the constructor

Changes: https://git.openjdk.org/jdk19/pull/85/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk19&pr=85&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8289252
  Stats: 14 lines in 1 file changed: 4 ins; 2 del; 8 mod
  Patch: https://git.openjdk.org/jdk19/pull/85.diff
  Fetch: git fetch https://git.openjdk.org/jdk19 pull/85/head:pull/85

PR: https://git.openjdk.org/jdk19/pull/85