In the general case, there may exist FilterNodes that are not sargable as a whole, but have individual AND/OR children that are sargable.

For instance, fiven the expression (a > 5 OR b < 10) AND (c = 33) AND (d regex 'acme.*corp'), the first term is a disjunction that is non sargable (until SERVER-69026 is done), but each of the individual comparison predicates {>, <, =} are sargable. So most of this expression can be estimated via histograms if they are available.

This task makes sure that each individual child is evaluated via a histogram whenever possible. The task also adds tests for various combinations of sargable/non-sargable nodes.