clean/split dhcp dmoessne config

[DanielFroehlich]

After migrating to KEA DHCP server onto sf1, we have lots of entries in the central /etc/kea/kea-dhcp4.conf
They belong to daniel and should move either in the "manual" config file or (I think I would prefer that) to a new "dmoessne-exclude.cong" (like we had back then with the inf1)

     /// Begin file /etc/dhcp/dhcpd-dmoessne-exclude-mac.conf
      # deny all KVM MAcs so they don't get a dhcp address
      /// match: substring(hardware, 1, 4)
      {
        "name": "dmoessne-reject"
//      "statement": {
//        "config": {
//          "value": "ignore",
//          "name": "allow-booting",
//          "code": 9
//        }
//      }
      },
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[rbo]

What I learned the last couple of days/weeks with Kea is that.

The reject dhcp stuff created during the migration is suboptimal:

part of client-classes

      # reject dhcp from secondary interface ucs57
      {
        "name": "sub#coe-reject#ucs57",
        "test": "substring(pkt4.mac,0,6) == 0x58ac780318b2"
      },

Following is much better:

part of reservations:

{ "hw-address": "58:ac:78:03:18:b2","client-classes": [ "DROP" ] },

We should consider a general config cleanup here