Cross-references from LSIF may not work on golang/go

Created by: creachadair

As part of RFC 122: Code Intel LSIF Delivery we are indexing a fork of the golang/go repository at sourcegraph-codeintel-showcase/go with LSIF.

With modifications, the lsif-go indexer is able to process the standard library packages, but I was not able to get precise hovercards to show up consistently in the UI. Figure out whether we are actually getting LSIF results (vs. LSP) for this repository, and if not figure out why.