Simplification of propagate_array_data_types:

No need to distinguish between ops for which we propagate the type of the
first input, and ops for which we require all inputs to have the same type
then propagate that type. Doing only the former is a mild relaxation of
what we've been doing, allows to drop much code, and makes this code far
less frequently needing to be updated again in the future as we drop a
long non-canonical list of operator types being special-cased.

PiperOrigin-RevId: 178156653