fix(db_stats.py): make get_scylla_version work on Debian like distros
fix(db_stats.py): make get_scylla_version work on Debian like distros

Currently get_scylla_version() uses rpm command to get packages list,
it doesn't work on Debian like distros.

Fixes #1868

Signed-off-by: Amos Kong <eb01d8f828a6c9a20be4534e72e049aaf41503df@scylladb.com>

scylladb/scylla-longevity-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-longevity-tests,scylladb/scylla-longevity-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests