[varnish] keep package files around
[varnish] keep package files around

Keeping one the created packages install is costly, so we do the next
best thing and keep them around, letting the user install them if they
really want it.

See for more info https://github.com/varnish/docker-varnish/commit/efa8f60de4abc4f388343bcc4088c2564aa89be7

docker-library/official-images,docker-solr/official-images,31z4/official-images,31z4/official-images,31z4/official-images,neo-technology/docker-official-images,docker-solr/official-images,docker-library/official-images,docker-library/official-images,infosiftr/stackbrew,31z4/official-images,neo-technology/docker-official-images,infosiftr/stackbrew,docker-library/official-images,docker-solr/official-images,infosiftr/stackbrew,infosiftr/stackbrew,infosiftr/stackbrew,docker-library/official-images,neo-technology/docker-official-images,docker-solr/official-images,infosiftr/stackbrew,neo-technology/docker-official-images,docker-library/official-images,infosiftr/stackbrew,neo-technology/docker-official-images,docker-solr/official-images,31z4/official-images,docker-library/official-images,31z4/official-images,docker-library/official-images,31z4/official-images,docker-solr/official-images,31z4/official-images,31z4/official-images,docker-solr/official-images,docker-library/official-images,neo-technology/docker-official-images,31z4/official-images,infosiftr/stackbrew,docker-solr/official-images,neo-technology/docker-official-images,docker-library/official-images,docker-library/official-images,infosiftr/stackbrew,docker-solr/official-images,docker-solr/official-images,docker-solr/official-images,31z4/official-images,31z4/official-images,infosiftr/stackbrew,neo-technology/docker-official-images,docker-library/official-images,neo-technology/docker-official-images,neo-technology/docker-official-images,neo-technology/docker-official-images,docker-solr/official-images,31z4/official-images,docker-library/official-images,infosiftr/stackbrew,neo-technology/docker-official-images,docker-solr/official-images,31z4/official-images,infosiftr/stackbrew,infosiftr/stackbrew,neo-technology/docker-official-images,docker-library/official-images,neo-technology/docker-official-images,docker-solr/official-images,infosiftr/stackbrew