Right now the draining sequence is
- stop transport (protocol servers, gossiper, streaming)
- shutdown tracing
- shutdown compaction manager
- flush CFs
- drain batchlog manager
- stop migration manager
- shutdown commitlog
This violates the layering -- both batchlog and migration managers
are higher-level services than the database, so they should be
shutdown/drained before it, i.e. -- before shutting down compaction
manager and flushing all CFs.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>