scylla_io_setup: hardcode the "mountpoint" YAML node to "/var/lib/scylla" for AMIs
scylla_io_setup: hardcode the "mountpoint" YAML node to "/var/lib/scylla" for AMIs

Signed-off-by: Vlad Zolotarov <976c0f8d0852ed6439ad273880b400a75a7c41d0@scylladb.com>

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