Ingest: Grok: duplicate patterns JAVACLASS and JAVAFILE

[jakelandis]

As discovered via Logstash : logstash-plugins/logstash-patterns-core#237

It appears that the Ingest Grok processor also has duplicated JAVACLASS and JAVAFILE definitions

https://github.com/elastic/elasticsearch/blob/6.5/libs/grok/src/main/resources/patterns/java

We should keep the top ones

JAVACLASS (?:[a-zA-Z$_][a-zA-Z$_0-9]*\.)*[a-zA-Z$_][a-zA-Z$_0-9]*
JAVAFILE (?:[A-Za-z0-9_. -]+)

and remove the lower ones.

[elasticmachine]

Pinging @elastic/es-core-infra

[ekalgolas]

Can I work on this?

[pendext]

I didn't see any movement on this since @ekalgolas commented a week ago, so I opened a PR, #35886