Merge branch 'ps/reftable-stack-compaction'

The code paths to compact multiple reftable files have been updated to correctly deal with multiple compaction triggering at the same time. * ps/reftable-stack-compaction: reftable/stack: handle locked tables during auto-compaction reftable/stack: fix corruption on concurrent compaction reftable/stack: use lock_file when adding table to "tables.list" reftable/stack: do not die when fsyncing lock file files reftable/stack: simplify tracking of table locks reftable/stack: update stats on failed full compaction reftable/stack: test compaction with already-locked tables reftable/stack: extract function to setup stack with N tables reftable/stack: refactor function to gather table sizes