Remove the final regdb_close() from net_conf.c

This is to hide the registry from net_conf.
Right now, it does not harm if "net conf" does not close
the registry file explicitly just before exiting.
I am working out a proper way of handling open/close
operations transparently in the libnet_conf library.

Michael
(This used to be commit 790ef78944)

source3/utils/net_conf.c

@@ -863,8 +863,6 @@ int net_conf(int argc, const char **argv)
 
 	ret = net_run_function2(argc, argv, "net conf", func);
 
-	regdb_close();
-
 	return ret;
 }