Processor type block_age always modifies slabs property "type" to bottom

The block_age processor always modify slabs property "type" to "bottom".

Steps to reproduce:

Because there are some offset, it's better to execute them in an enough open area.

1.  Create a new Classic Flat world and add this data pack.

2.  These blocks are not processed:

   /place template test:stone_brick_slab_state_type_bottom
   /place template test:stone_brick_slab_state_type_double
   /place template test:stone_brick_slab_state_type_top

3.  These blocks are processed:

   /place structure test:stone_brick_slab_state_type_bottom
   /place structure test:stone_brick_slab_state_type_double
   /place structure test:stone_brick_slab_state_type_top

4. Check the property "type" of them.

Expected results:

Not processed slabs type are bottom, double, top.

Processed slabs type are bottom, double, top.

Observed results:

Not processed slabs type are bottom, double, top.

Processed slabs type are bottom, bottom, bottom.