sstables: Fix resharding by not filtering out mutation that belongs to other shard
sstables: Fix resharding by not filtering out mutation that belongs to other shard

After 301358e, sstable resharding stopped work because shared sstables would
use a filtering reader, which excludes mutation that belong to other shards.
That completely breaks which relies on compaction of mutations that belong
to different shards. The fix is about using recently introduced non local
shard reader.

Fixes #3041.

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

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