streamline some log levels for invalid servicenames

streamline some log levels for invalid servicenames

I don't think we need to log the fact that a user gave a wrong sharename in Explorer with the highest log level.
The level of this was not very consistent:
service.c:		DEBUG(3,("find_service() failed to find service %s\n", service));
service.c:		DEBUG(0,("%s (%s) couldn't find service %s\n",
smb2_tcon.c:		DEBUG(1,("smbd_smb2_tree_connect: couldn't find service %s\n",

This changes the last two to 3 as the first one.

Signed-off-by: Christian Ambach <christian.ambach@de.ibm.com>