tests: new demo record with CSV data files

* Adds new demo record with several CSV data files and ZIP files.
  (closes #1927) (PR #2208)

* Fixes `test_legacy_record.py` accordingly.

Reviewed-by: Tibor Simko <tibor.simko@cern.ch>
Signed-off-by: Antonios Manaras <antonios.manaras@cern.ch>