[release/v1.6] Update outdated java span profile information

[github-actions[bot]]

Backport fa05d6bd59c1db5b09ae5e211723ad7d2fb09b70 from #3339

---

I had been going through those docs with one of our customers, I think the code blocks are very confusing and I think settings should be set using environment variables.

I do hope I did not misunderstand anything.