On 'product != scylla' environment, we have a bug with .default file
(sysconfig file) handling.
Since .default file should be install original name, package name can be
doesn't match with .default filename.
(ex: default file is /etc/default/scylla-node-exporter, but
package name is scylla-enterprise-node-exporter)
When filename doesn't match with package name, it should be renamed with
as follows:
<package name>.<filename>.default
We already do this on .service file, but mistakenly haven't handled
.default file, so let's add it too.
Related scylladb/scylla-enterprise#1718
Fixes#8527Closes#8528