[9.4] (backport #19010) require java 21, since jruby 10 requires it

[mergify]

Release notes

Sets the minimum version of Java to 21.

What does this PR do?

Updates the check in the JVMOptionsParser to provide helpful output when logstash is invoked with a JVM that does not meet JRuby 10's minimum requirement.

Why is it important/What is the impact to the user?

Without this, invoking Logstash on JVM 17 produces an obscure and unhelpful error message:

╭─{ rye@perhaps:~/src/elastic/logstash@main }
╰─● (jenv shell 17; bin/logstash -e '')
Using system java: /Users/rye/.jenv/shims/java
Error: Unable to initialize main class org.logstash.Logstash
Caused by: java.lang.UnsupportedClassVersionError: org/jruby/exceptions/RaiseException has been compiled by a more recent version of the Java Runtime (class file version 65.0), this version of the Java Runtime only recognizes class file versions up to 61.0
[error: 1] 

With it, the message is helpful and clear:

╭─{ rye@perhaps:~/src/elastic/logstash@main (require-java-21 ✘) }
╰─● (jenv shell 17; bin/logstash -e '')
Using system java: /Users/rye/.jenv/shims/java
The minimum required Java version is 21; your Java version from [/opt/homebrew/Cellar/openjdk@17/17.0.15/libexec/openjdk.jdk/Contents/Home] is [17] and does not meet this requirement
[error: 1]

Checklist

• My code follows the style guidelines of this project
• [ ] I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• [ ] I have made corresponding change to the default configuration files (and/or docker env variables)
• [ ] I have added tests that prove my fix is effective or that my feature works

How to test this PR locally

• Build Logstash normally with Java 21
• Launch Logstash with Java 17
  • jenv: (jenv shell 17; bin/logstash -e "")
  • LS_JAVA_HOME LS_JAVA_HOME=/path/to/java17 bin/logstash -e ""

Related issues

• Bump JRuby to 10.x #18755

Use cases

---

This is an automatic backport of pull request #19010 done by [Mergify](https://mergify.com).

[github-actions]

🤖 GitHub comments

Just comment with:

• run docs-build : Re-trigger the docs validation. (use unformatted text in the comment!)
• run exhaustive tests : Run the exhaustive tests Buildkite pipeline.

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: 2aea6dc

cc @yaauie

[yaauie]

Auto-backport clean and green 💚✅