Merge branch 'ps/reftable-stack-tempfile'

The code in reftable backend that creates new table files works better with the tempfile framework to avoid leaving cruft after a failure. * ps/reftable-stack-tempfile: reftable/stack: register compacted tables as tempfiles reftable/stack: register lockfiles during compaction reftable/stack: register new tables as tempfiles lockfile: report when rollback fails