Clarify G1GC support on docs

[dliappis]

As of 6.5.0, G1GC is now supported by Elasticsearch.

We should document this, perhaps in the setup page.

[elasticmachine]

Pinging @elastic/es-docs

[elasticmachine]

Pinging @elastic/es-core-infra

[bczifra]

Related: #41358

[jrodewig]

[docs issue triage]

Leaving this open as it's still relevant.

[williamrandolph]

@jrodewig @debadair Is this issue still relevant? It looks like we have some discussion of garbage collectors on the page about the serial collector check: https://www.elastic.co/guide/en/elasticsearch/reference/7.10/_use_serial_collector_check.html

That paragraph mentions that we default to using G1GC, and that CMS will only be used if you don't use the JVM shipped with Elasticsearch.

[jrodewig]

Thanks for the ping @williamrandolph.

I'm going to close this issue. With #49123, we now default to G1GC for JDK 14+. With #59667, Elasticsearch 7.11+ ergonomically adjusts G1GC options based on heap size.

While users can manually adjust G1GC options, I don't think we should encourage it or document it in depth. That effort can be covered in #53889.