Merge branch 'updater-interactive-service-config' into 'stable-3.1'

added request for DB Server on update

Please review this as I don't know if there was any incompatible reason why db was always enabled hard coded or if it's just as it would have been detected anyways as it's always on a ISPC-Server.

If you and ISPC are fine with probably getting a value `$conf['services']['db']` which is `false` on user behalf, then just merge without any further request.

Merging this really and ultimately fixes ispconfig/ispconfig3#4050

See merge request !437