fix(opnsense): correct Kea leases4 del_lease endpoint — path param, not body

The lease-delete call never actually worked: it posted {"ip-address": ip}
to /api/kea/leases4/delLease, both wrong. Verified live against a real
OPNsense instance while cleaning up stale leases left by failed NetOrk VM
provisioning attempts — every call returned {"status": "error", "message":
"Missing lease IP parameter"} despite three different body-parameter
guesses (ips as list, ips as string, ip singular). The official API docs
(docs.opnsense.org/development/api/core/kea.html) show LeasesController as
"Abstract [non-callable]" with a del_lease($ips=null) action; despite that
signature looking like a body field, the concrete leases4 route only
accepts the IP as a URL path segment: POST /api/kea/leases4/del_lease/{ip}
confirmed {"status": "ok"} and the lease actually gone from a follow-up
search.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

tests/unit/test_driver.py

@@ -1379,8 +1379,14 @@ class TestDeleteDhcpReservationAndLease:
         reconfigure_call = driver.session.post.call_args_list[2]
         assert reconfigure_call.args[0] == "https://opnsense.example.com/api/kea/service/reconfigure"
         del_lease_call = driver.session.post.call_args_list[3]
-        assert del_lease_call.args[0] == "https://opnsense.example.com/api/kea/leases4/delLease"
-        assert del_lease_call.kwargs["json"] == {"ip-address": "172.22.8.253"}
+        # IP is a URL path segment, not a JSON body field — verified live
+        # against a real OPNsense instance; a {"ips": [ip]} body (the
+        # natural reading of the documented del_lease($ips=null) signature)
+        # returns {"status": "error", "message": "Missing lease IP parameter"}.
+        assert (
+            del_lease_call.args[0]
+            == "https://opnsense.example.com/api/kea/leases4/del_lease/172.22.8.253"
+        )
 
     def test_noop_when_no_reservation_and_no_lease_found(self, driver):
         driver.session.post.return_value = _make_json_response({"rows": []})