This kind of data is not used except in tests where it is used only to
create databases that don't match actual usage of aristo.
Removing simplifies future optimizations that can focus on processing
specific leaf types more efficiently.
A casualty of this removal is some test code as well as some proof
generation code that is unused - on the surface, it looks like it should
be possible to port both of these to the more specific data types -
doing so would ensure that a database written by one part of the
codebase can interact with the other - as it stands, there is confusion
on this point since using the proof generation code will result in a
database of a shape that is incompatible with the rest of eth1.
58cde36656