R1:7f6508af5a3d

Add missing execution on archived task query

Summary: Fixes T8599. I'm not sure how to reproduce the original issue, but I'm fairly confident that the issue is that the issue is that `execute()` is not called on the query object.

Test Plan: Created a Harbormaster build plan with a single "Lease Host" step. Ran `./bin/harbormaster build --plan 1 D1` from the command line and hit the exception as described in T8599. Applied patch and hit a different exception (which I think is just because I don't know how…