wireproto: bypass filechunkiter for small files when streaming Merely creating and using a generator has a measurable impact, particularly since the common case for stream_out is generators that yield just once. Avoiding generators improves stream_out performance by about 7%.

wireproto: don't audit local paths during stream_out Auditing at this stage is both pointless (paths are already trusted by the local repo) and expensive. Skipping the audits improves stream_out performance by about 15%.