Review auto-configuration that accepts both a URI and separate properties

As identified by https://github.com/spring-projects/spring-boot/issues/41231, we should review our auto-configuration in the places where it accepts both a URI and separate properties as there's the potential for some confusion and inconsistency.

Upon initial inspection, it would appear that the Neo4j auto-configuration ignores any user info in its URI and only uses the separate username and password properties for authentication. The Elasticsearch auto-configuration does things differently as it uses any user info in the configured URI(s) with the separate username and password being used as a fallback. Part of this is differences in the underlying services leaking out into Boot's properties but I think a review is still warranted as we should try to make things as consistent as possible and document any remaining inconsistencies.

Start by locating the Neo4j and Elasticsearch auto-configuration entry points and their URI, username, and password property handling. Compare how each configuration resolves credentials, then review the related property documentation for inconsistencies. Done means the behavior is made as consistent as the underlying services allow and any remaining differences are documented.