nix: drop duplicate centralToggleOff fixture from rebase conflict

The rebase onto main resolved an additive conflict in
module-eval.nix by keeping both fixture blocks, leaving
centralToggleOff defined twice and failing nix flake check with
'attribute centralToggleOff already defined'. Drop the later
duplicate; the earlier definition already covers every downstream
case that references it.

nix/module-eval.nix

@@ -502,14 +502,6 @@ let
     }
     ).allowedTCPPorts;
 
-  # A host that installs the modules and turns nothing on. The per-service
-  # deployment toggles are what decide whether the swarm-level services render
-  # here, and none of them is derived from the hive being on, so this renders
-  # the same absences `bare` does — the arms below assert both, because a
-  # service that had quietly become unconditional would still look right on
-  # only one of them.
-  centralToggleOff = hive { enable = false; };
-
   # Ports asked for on such a host. The request is the whole condition: the
   # firewall hole exists because an operator named a port, not because the
   # hive is running, and an agent reaching a host service is a claim about