Cleanup is about rewriting a sstable discarding any keys that
are irrelevant, i.e. keys that don't belong to current node.
Parameter cleanup was added to compact_sstables.
If set to true, irrelevant code such as the one that updates
compaction history will be skipped. Logic was also added to
discard irrelevant keys.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>