Deliver a dead letter again only where it is received, and never stop serving for the notices

A dead letter was let go as delivered even when its consumer did not filter
its again subject; seat asks needed a grant over every seat's queue and left
the original stuck; a notices bind failure stopped the controller (review).

cmd/mesh-controller/probes.go

@@ -878,6 +878,10 @@ func streamDiffers(want broker.Stream, have nats.StreamConfig) string {
 	if want.MaxBytes > 0 && have.MaxBytes != want.MaxBytes {
 		differs = append(differs, fmt.Sprintf("holds up to %d bytes, defined %d", have.MaxBytes, want.MaxBytes))
 	}
+	if want.DuplicatesSeconds > 0 && have.Duplicates != time.Duration(want.DuplicatesSeconds)*time.Second {
+		differs = append(differs, fmt.Sprintf("keeps one of a message id for %s, defined %s", have.Duplicates,
+			time.Duration(want.DuplicatesSeconds)*time.Second))
+	}
 	if want.DiscardNew && have.Discard != nats.DiscardNew {
 		differs = append(differs, "drops what it holds when full, defined to refuse what comes next")
 	}