Merge branch 'tb/combine-cruft-below-size'

Merge branch 'tb/combine-cruft-below-size'

"git repack" learned "--combine-cruft-below-size" option that
controls how cruft-packs are combined.

* tb/combine-cruft-below-size:
  repack: begin combining cruft packs with `--combine-cruft-below-size`
  repack: avoid combining cruft packs with `--max-cruft-size`
  t/t7704-repack-cruft.sh: consolidate `write_blob()`
  t/t7704-repack-cruft.sh: clarify wording in --max-cruft-size tests
  t/t5329-pack-objects-cruft.sh: evict 'repack'-related tests