lcs: remove useless expensive check for overlapping L1 sstables
lcs: remove useless expensive check for overlapping L1 sstables

there's no way a L1 sstable will be in candidates set which was
previously built from list of L0 sstables.

Signed-off-by: Raphael S. Carvalho <1e2942cea40e3b4d2162dfcd9e53e41c05a84d22@scylladb.com>

scylladb/scylla,avikivity/scylla,duarten/scylla,scylladb/scylla,scylladb/scylla,avikivity/scylla,avikivity/scylla,duarten/scylla,duarten/scylla,scylladb/scylla