DataConverter incorrectly placed a fall_distance value with 0.0
if the entity did not have a FallDistance entry. This results in the
entity spawn data having 2 entries, which prevents finalisation
logic from running.
We can fix this by removing the fall_distance entry if it is 0.0.
In 1.21.8 there will be a proper fix for this and the patch can be
dropped.
04f95191f1