main: add generating missed mv updates from staging sstables
main: add generating missed mv updates from staging sstables

If any sstables are found in the staging directory, it means that
they missed generating view updates, so it's performed now.

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