codeintel: set COURSIER_CACHE env var for coursier invocations in gitserver
Created by: Strum355
Context in #24502 (closed)
This PR adds a new env var, SRC_COURSIER_CACHE
, that is passed through to coursier invocations as COURSIER_CACHE
if set.
It is expected to be set for gitserver on dot-com to a persistent volume mount.