The VmHost model requires a Sshable record due to database constraints.
Currently, we're creating VmHost models with dummy Sshable data across
multiple test locations, leading to code duplication.
Additionally, we're creating VmHost instances using `VmHost.create(...)
{ _1.id = Sshable.create.id }`, which results in VmHost having a Sshable
UBID instead of its own UBID. While this doesn't break any test, it's
conceptually incorrect and should be fixed.
e1286b290a