<i18n dev> RFR: 8303275: Use {@Return and @linkplain in Locale and related classes [v2]

[Justin Lu]

> This PR modifies the javadoc of methods in Locale, LocaleServiceProvider, and LocaleServiceProviderPool to use {@return and @linkplain.

Justin Lu has updated the pull request incrementally with one additional commit since the last revision:

  Remove prefix Locale for in-class linkplains

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Changes:
  - all: https://git.openjdk.org/jdk/pull/12780/files
  - new: https://git.openjdk.org/jdk/pull/12780/files/cfbbfa0a..5850ca02

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12780&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12780&range=00-01

  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/12780.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12780/head:pull/12780

PR: https://git.openjdk.org/jdk/pull/12780