Implement auto-inference for Java package repositories.
Created by: olafurpg
Fixes #20835 (closed). Previously, we had to manually add auto-indexing
configuration for Java package repositories. This commit implements
auto-inference for repos that have a lsif-java.json
file at the root
directory. These repositories are created by the new JVM Dependencies
external service type and they should have a high likelyhood of indexing
successfully.
If this change works out well in production, we can consider expanding the pattern list to also match Gradle/Maven builds.