MaxScale reads hidden files from maxscale.cnf.d

If you setup and use /etc/maxscale.cnf.d, it will include files:

• example.cnf
• .example.cnf
• .directory/example.cnf

This is a problem if you use a kubernetes persistent volume mapped to a configmap (containing say example.cnf=...) because you will end up with the following actually on disk:

• example.cnf
• .<GUID>/example.cnf

Maxscale then won't startup because it loads both and has duplicate configurations. I think the logic to find the cnf files should exclude all hidden files and directories as i can't think of a good reason why anyone would want to do that.

To workaround this i used the configdir argument to load from a specific directory but this means i can only support one file.