REF: simplify json get_values
cc @WillAyd trying to get away from _internal_get_values in the json code; this is zero-logic-changing to narrow the scope of what gets passed to _internal_get_values.

AFAICT replacing the _internal_get_values call with calling `__array__` doesnt break any tests, but in general the two are not always equivalent and it isnt obvious to me whether there are untested cases where it matters.