Fix `rpm` make target for split config. (#2084)
Fix `rpm` make target for split config. (#2084)

After #2069 landed we no longer have a `boulder-config.json` file. This breaks the `make rpm` flow because the `rpm` make target has an explicit reference to this file as an argument to `fpm`.

This commit replaces the `test/boulder-config.json` reference with its replacement, the `test/config/` directory.
ibukanov/boulder,ZCloud-Firstserver/boulder,letsencrypt/boulder,bmw/boulder,sophie-h/boulder,jsha/boulder,jsha/boulder,benileo/boulder,lucasallan/boulder,jcjones/boulder,ZCloud-Firstserver/boulder,ibukanov/boulder,lucasallan/boulder,jfrazelle/boulder,jcjones/boulder,jfrazelle/boulder,letsencrypt/boulder,jcjones/boulder,ZCloud-Firstserver/boulder,sophie-h/boulder,lucasallan/boulder,jfrazelle/boulder,letsencrypt/boulder,bmw/boulder,benileo/boulder,benileo/boulder,benileo/boulder,ZCloud-Firstserver/boulder,sophie-h/boulder,ibukanov/boulder,jfrazelle/boulder,jsha/boulder,bmw/boulder,jcjones/boulder