ftpserver: lower the normal DATA connect timeout to speed up torture tests

- tests/ftpserver.pl blocks when expecting a DATA connection from the
  client.

- the previous 10 seconds were encountered repeatedly in torture tests
  and let to long waits.

- 2 seconds should still be sufficient for current hw, but CI will show.

Closes #10178

tests/ftpserver.pl

@@ -2577,7 +2577,7 @@ sub PASV_ftp {
         local $SIG{ALRM} = sub { die "alarm\n" };
 
         # assume swift operations unless explicitly slow
-        alarm ($datadelay?20:10);
+        alarm ($datadelay?20:2);
 
         # Wait for 'CNCT'
         my $input;