Exclude unnecessary files in gitlab-grpc gem
Exclude unnecessary files in gitlab-grpc gem

When the gitlab-grpc gem gets merged into GitLab via
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/82766, the
installed libraries take over 300 MB of source data and compiled
objects. These files are not needed for Omnibus, so exclude them as we
do with the grpc gem.

Part of https://gitlab.com/gitlab-org/omnibus-gitlab/-/issues/6687

Changelog: added

gitlabhq/omnibus-gitlab,gitlabhq/omnibus-gitlab,gitlabhq/omnibus-gitlab,gitlabhq/omnibus-gitlab