Delete definition of metric `consul.acl.blocked.node.registration`

Although the metric is defined, there is no code which ever sets its
value - the code in question is genuinely asymmetric - there are 3 types
of object for which registration can be tracked, but only 2 for which
deregistration can be tracked.

agent/local/state.go

@@ -46,10 +46,6 @@ var StateCounters = []prometheus.CounterDefinition{
 		Name: []string{"acl", "blocked", "node", "registration"},
 		Help: "Increments whenever a registration fails for a node (blocked by an ACL)",
 	},
-	{
-		Name: []string{"acl", "blocked", "node", "deregistration"},
-		Help: "Increments whenever a deregistration fails for a node (blocked by an ACL)",
-	},
 }
 
 const fullSyncReadMaxStale = 2 * time.Second