Fix bug when empty input_dates for some periods; linked to filtering of inputs relative to the simulation period

LMDZ is making good progress; stuck because of satellites and what to extract from LMDZ: airm? hlay?

Changing seed to have better coverage with observations for dummy tests; re-activating all tests for dummy

Fix side-effects when running several obs operators in a raw by resetting the datastore each time; check if one wants to propagate data from one execution to the next one?