R1:4cf1270ecdd8

In Harbormaster, make sure artifacts are destroyed even if a build is aborted

Summary:
Ref T9252. Currently, Harbormaster and Drydock work like this in some cases:

# Queue a lease for activation.
# Then, a little later, save the lease PHID somewhere.
# When the target/resource is destroyed, destroy the lease.

However, something can happen between (1) and (2). In Drydock this window is very short and the "something" would have to be a lighting strike or something similar, but in Harbormaster we…