Clear out bogus DB partition info on default reload.
The new d710s have a single-partition image as their default. As a result, when they were reloaded, the info for the other partitions (in particular partition 1) was not being cleared. So if I were to break my install of FBSD72-STD on a d710 node and then free it, the reload would not clear the partition 1 info in the DB. If someone else came along requesting FBSD72-STD and got that node assigned, os_load would think that it didn't need to reload partition 1 and just boot right into the old stale partition. Now for a "default" reload (i.e., from reload_daemon), a single partition load will clear all the other partitions. We don't do this all the time since a user might want to reload one of the partitions on their allocated node without clobbering the others.