R1:99889a6321a7

Execute Harbormaster buildable filtering properly from HarbormasterBuildSearchEngine

Summary:
Ref T11473. When running `harbormaster.build.search` with a `buildables` constraint, the constraint doesn't get passed to the Query and so currently has no effect.

This piece of logic was just accidentally omitted from D16356. It is probably not used anywhere today and doesn't show up in the UI, so it's easy to overlook (I missed it in review, too).

Test Plan: Ran `harbormaster.build.search` with a `buildables`…