they're used to stop all ongoing compaction on behalf of a given table
T. Today, each table has a single table_state representing it, but after
we implement compaction groups, we'll need to call the procedure for
each group in a table. But the discussion doesn't belong here, as
compaction group work will only come later. By the time being, we're
only making compaction manager fully switch to table_state.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>