bucket discovery: no name guessing

Remove all fabricated candidate names (suffixes and the wordlist). Discovery now
only tests names that actually occur in the incoming hostname: the subdomain
label and the registrable-domain label (assets.example.com -> assets, example).
Nothing is permuted or drawn from a wordlist.

cmd/ctcloud/main.go

@@ -167,16 +167,8 @@ func run() error {
 			},
 		})
 		discoverer.Start(ctx)
-		wordlist := 0
-		if cfg.BucketScanWordlist {
-			for _, name := range discover.Wordlist() {
-				discoverer.SubmitName(name)
-			}
-			wordlist = len(discover.Wordlist())
-		}
 		slog.Info("bucket name discovery enabled", "event", "startup",
-			"qps", cfg.BucketScanQPS, "workers", cfg.BucketScanWorkers, "do_spaces", cfg.BucketScanDO,
-			"wordlist", wordlist)
+			"qps", cfg.BucketScanQPS, "workers", cfg.BucketScanWorkers, "do_spaces", cfg.BucketScanDO)
 	}
 
 	var prober *probe.Prober