"not equals" conditions should be passed to the index

With OAK-2529 fixed, conditions of the form "x <> 1" are passed to the index (via the filter condition) as "x is not null". This is sufficient if there are many distinct values for "x", but is bad if there are only few distinct values, and many nodes with value 1.

Therefore, the "x <> 1" condition should be passed to the index directly.

The existing indexes will need to be changed to deal with this case (possibly including the property and ordered index), so that the correct result is returned, and so that the condition is actually used.