Re #8359. Avoid a memory leak when updateFacilities() is called.

It starts by clearing the list of facilities (which contains owned pointers
to FacilityInfo objects), but didn't delete the held objects.
Re #8359. Add suppression of a leak that's actually within Nexus.

It appears nexus gives a nice big leak if you try to open a file that isn't
an HDF file. There's nothing we can directly do about that.