* chore(weed/util/chunk_cache): remove unused functions
* fix(chunk_cache): bound ReadAt buffer in readNeedleSliceAt
When the caller-provided buffer is larger than the remaining needle
bytes, ReadAt would spill into the next needle and trigger the
n != wanted error. Slice to data[:wanted] so the read stops at the
needle boundary.
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Co-authored-by: Chris Lu <chris.lu@gmail.com>