table: filter_sstable_for_reader: allow clustering filtering md-format sstables
table: filter_sstable_for_reader: allow clustering filtering md-format sstables

Now that it is safe to filter md format sstable by min/max column names
we can remove the `filtering_broken` variable that disabled filtering
in 19b76bf75bd8197f1e7aa2327323a0fa90d5d13f to fix #4442.

Signed-off-by: Benny Halevy <23c997c90eb8537635e9392d48e7af1bf1b2ca22@scylladb.com>

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