alpine: don’t hardcode nftables input rule for SSH

Instead configure it in NetBox like all other services.

roles/alpine/templates/local.nft.j2

@@ -1,7 +1,5 @@
 table inet filter {
     chain input {
-        tcp dport ssh accept
-
 {% for service in services %}
 {% set prefixes = service | allowed_prefixes %}
 {% set ports = service.ports | compact_numlist %}