Two leftovers from pnpm/pnpm#14189, both behaviour-neutral.
`artifactBlobDigest` was a pass-through around a private `blobId` that did
the actual work, so the digest had two names and the doc comment sat on
neither the definition nor every call site. There is now one exported
function; the three call sites that only wanted the integrity validated
call it and discard the result, as they did before under the other name.
The restore's store lookup tested `!downloaded.contains_key` and then the
download below tested it again, so a reader had to hold both in mind to see
that the lookup only runs when the bytes are not already in memory. Folding
the lookup into the download's own branch says it once. `blob_id`'s error is
propagated rather than swallowed by `if let Ok(..)`: the manifest validator
rejects a malformed integrity long before hydration, so this is unreachable,
and a silent fall-through to downloading is a worse way to express that than
a `?`.
Follow-up to pnpm/pnpm#14189.
Zoltan Kochan
d278429ba9