fix(i/t/tor.go): show correct command line (#673)

While there, ensure that we print a warning if we cannot find
the correct tor binary.

Work part of https://github.com/ooni/probe/issues/1917.

internal/tunnel/tor.go

@@ -72,7 +72,6 @@ func torStart(ctx context.Context, config *Config) (Tunnel, error) {
 	extraArgs = append(extraArgs, "notice stderr")
 	extraArgs = append(extraArgs, "Log")
 	extraArgs = append(extraArgs, fmt.Sprintf(`notice file %s`, logfile))
-	config.logger().Infof("tunnel: tor: exec params: %s %+v", stateDir, extraArgs)
 	torStartConf, err := getTorStartConf(config, stateDir, extraArgs)
 	if err != nil {
 		return nil, err