fix(internal/serviceconfig): backfill api path for Go where explicitly restricted (googleapis#3990)

Followup to googleapis#3960, now that
for google/cloud apis when Languages are explicitly listed, it is an
allow list for generate.

This change added LangGo to API list where language is already explicit,
comparing `librarian.yaml` generated by `migrate .` in google-cloud-go.
Note this is not a full list as migration is not fully done, path e.g.,
google/datastore/v1 are not included in this list yet.

Fix googleapis#3872

Author: zhumin8