[core] Fix data evolution scan pruning files after a column type change

[ArnavBalyan]

Purpose

• Data data evolution drops the rows when a column type/nullability changes
• This is because evolutionStats leaves the -1 offset for a column whose stored type differs from the current type, which DataEvolutionArray encodes as all null.
• LeafPredicate then prunes the pre alter version of the file and loses rows.
• Correct such columns to the -2 so the file is kept

Tests

• UT