* refactor: document and improve `MockIngesterConnection`
* refactor: split `OldOneMeasurementFourChunksWithDuplicates` for `EXPLAIN` queries
* fix: mark "IngsterPartition" chunks as unsorted
* fix: "group by" queries may require sorted comparison
* refactor: re-export a few more types from querier
* fix: ensure that test parquet files are de-duped
* test: chunks in ingester stage
* docs: explain test code
Marco Neumann