RFR: 8300586: Refactor code examples to use @snippet in java.text.Collator

[Justin Lu]

This PR implements _JEP 413: Code Snippets in Java API Documentation_ for [java.text.Collator](https://docs.oracle.com/en/java/javase/19/docs/api/java.base/java/text/Collator.html).

Code examples using <pre> ... </pre> blocks are replaced with the @ snippet syntax where applicable.

Additionally, the code examples have been slightly tweaked to increase readability.

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Commit messages:
 - Minor tweak to second code block
 - Swap to snippet, (c) year, update first code block

Changes: https://git.openjdk.org/jdk/pull/12080/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12080&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8300586
  Stats: 10 lines in 1 file changed: 1 ins; 0 del; 9 mod
  Patch: https://git.openjdk.org/jdk/pull/12080.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12080/head:pull/12080

PR: https://git.openjdk.org/jdk/pull/12080