R1:918ac5755c78

Limit maximum size of Owners package queries

Summary:
Currently, a change may affect a very large number of paths. When we run the OwnersWorker on it, we'll execute a query which looks up packages for the paths. This may exceed "max_allowed_packet". Instead, break the list of paths into smaller chunks.

This is mostly to unblock r4nt / llvm, I'm going to add a more finessed approach to array_chunk() shortly.

Test Plan: Ran `reparse.php --owners` on a revision which affected packages, verified results are…