Remove deprecated SSL settings from Elasticsearch output

[robbavey]

• Create branch from most recent commit on main
• All plugin changes that remove SSL settings should be in a new major release of the plugin
• Mark old SSL settings as obsolete
• Add breaking change entry to plugin changelog
• Add details of change to the 9.0 breaking changes documentation in core.
• Verify that any integration tests in core that rely on SSL settings still work. Fix any broken integration tests
• Verify plugin documentation, remove any references to deprecated settings

[donoghuc]

See #1118 for original standardization work.

[donoghuc]

Logstash docs PR elastic/logstash#16787

UPDATE: Merged