[DOCS] Drop these unused references

[joegallo]

Related to #83423

#105406 actually deletes the very last vestiges of the code, but there's still a few grep hits in the docs. This PR drops those, too. Here's an after:

joegallo@simulacron:~/Code/elastic/elasticsearch $ git grep javadoc-license
joegallo@simulacron:~/Code/elastic/elasticsearch $ git grep javadoc-watcher
joegallo@simulacron:~/Code/elastic/elasticsearch $ git grep rest-high-level-client-javadoc
joegallo@simulacron:~/Code/elastic/elasticsearch $

---

This reference remains (which you can see in the live docs here), but it indirectly gets the user to the Java API Client eventually, so I think it's fine to stay:

joegallo@simulacron:~/Code/elastic/elasticsearch $ grep -B6 -A1 rest-high-level -- docs/reference/redirects.asciidoc
[role="exclude",id="java-clients"]
=== Java transport client and security

The Java transport client has been removed. Use the
https://www.elastic.co/guide/en/elasticsearch/client/java-rest/7.15/java-rest-high.html[Java
high-level REST client] instead. For migration steps, refer to the
https://www.elastic.co/guide/en/elasticsearch/client/java-rest/7.15/java-rest-high-level-migration.html[migration
guide].

[github-actions]

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[elasticsearchmachine]

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