fix suffix range handling in cached object store get_opts

[naruto-lgtm]

Closes #

Repro: read any cached parquet object with a suffix range (bytes=-N) through MemCachedObjectStore, then compare with the same read against the backing store. They disagree.

Cause: get_opts hand-rolls the GetRange to byte-offset conversion and maps Suffix(n) to 0..n, so it returns the first n bytes instead of the last n. The same match also errors on a bounded range whose end runs past the object rather than clamping it, which diverges from the ObjectStore contract that get_ranges/the inner store follow.

Fix: delegate to object_store's own GetRange::as_range(len), which implements the documented Suffix/Offset/Bounded semantics, so a cache hit returns the same bytes as the backing store. Added a regression test over all three range kinds.

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[naruto-lgtm]

any update?

[naruto-lgtm]

any update?