Remove legacy MBQL syntax in tests (#26309)

* [:field-id id] => [:field id nil] or $name. Except places where tests
are meant to check normalization

* [:datetime-field [:field id] unit] -> [:field id {:temporal-unit unit}]
or !unit.name

* [:fk-> [:field 1] [:field 2]] => [:field 2 {:source-field 1}]