Reduce memory footprint for large monorepos

[efritz]

scip-go chokes at some point indexing large monorepos. This customer ran into an issue where on a 60M SLOC monorepo, they couldn't index a project using 32GB RAM, but 128GB was enough. Slack thread with discussion

$ scip-go -vvv
Resolving module name
Finished in 116.02ms.

Go standard library version:  go1.18
Resolved module name       : <REDACTED>

Loading Packages
Finished in 20m29s.

Indexing Implementations
Finished in 42m32s.

[1]    13783 killed     scip-go -vvv

$ echo $?
137