system: limit /conf/config.xml access to administrators

[fichtner]

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Is your feature request related to a problem? Please describe.

Today all consumers of /conf/config.xml should be administrators, but the permissions for /conf/config.xml are allowing general access to the file.

Describe the solution you like

Backups have recently been addressed and now do the same for the main configuration file.

Describe alternatives you considered

N/A

Additional context

N/A