athinfo.defs should use better test for cluster machines

[jdreed]

As per release-team discussion, "machtype -v -L | grep debathena-cluster" is not a valid test for "Is this machine public". Under Athena 9, we tested for PUBLIC=true in rc.conf. This value was set regardless of whether the machine installed successfully. By contrast, if something breaks during the install, it's possible for machtype -L to report the wrong value.

We should move to some sort of flag file, whether this is the PXE install flag, or a new file, but a cluster machine should successfully expose its logs over athinfo even if it's broken.

[jdreed]

Fixed in r25057/8, where I ship a script that will return 0 if it's a cluster machine or 1 otherwise, so queries can do:

/usr/lib/athinfod/is_cluster && whatever

We should ship the script in athinfod, not -cluster-athinfod-config, so that it's guaranteed to be there.

[jdreed]

athinfod-10.0.0-0debathena16 -> dev