Merge branch 'jt/reftable-geometric-compaction'

The strategy to compact multiple tables of reftables after many operations accumulate many entries has been improved to avoid accumulating too many tables uncollected. * jt/reftable-geometric-compaction: reftable/stack: use geometric table compaction reftable/stack: add env to disable autocompaction reftable/stack: expose option to disable auto-compaction