389-ds-base doesn't list Cockpit as an optional dependency
The 389-ds-base
package ships a plugin for Cockpit allowing for administration through the Cockpit UI, but there's no mentioning in the dependency list that this plugin is being shipped or this optional feature is made available.
It would need something akin to the following added:
optdepends=('cockpit: LDAP administration through the Cockpit web UI')