[MC-145113] Falling blocks passengers land inside a block and not on top of block, that destroys "only one command creations" too

The bug

When summoning a falling block with another entity as a passenger (that passenger could be another falling block as well), that passenger will be inside of the block once the block lands on the ground. Before 1.14, it used to be ejected on top of the block.

Most noteworthy, this causes falling blocks riding other falling blocks to pop off as items instead of being placed, rendering so-called "one command creations" unusable.

How to reproduce

1. Example:

/summon minecraft:falling_block ~5 ~10 ~ {Time:1,BlockState:{Name:"minecraft:redstone_block"},Passengers:[{id:"minecraft:cow"}]}

→ The cow will be inside of the block once the block lands

2. Example:

/summon minecraft:falling_block ~5 ~10 ~ {Time:1,Passengers:[{id:"minecraft:falling_block",Time:1,Passengers:[{id:"minecraft:falling_block",Time:1,Passengers:[{id:"minecraft:falling_block",Time:1}]}]}]}

→ The sand blocks will be drop of the block once the first block lands

3. Example with more blocks:

/summon minecraft:falling_block ~5 ~10 ~ {Time:1,Passengers:[{id:"minecraft:falling_block",Time:1,Passengers:[{id:"minecraft:falling_block",Time:1,Passengers:[{id:"minecraft:falling_block",Time:1,Passengers:[{id:"minecraft:falling_block",Time:1,Passengers:[{id:"minecraft:falling_block",Time:1,Passengers:[{id:"minecraft:falling_block",Time:1,Passengers:[{id:"minecraft:falling_block",Time:1,Passengers:[{id:"minecraft:falling_block",Time:1}]}]}]}]}]}]}]}]}

→ The sand blocks will be drop of the block once the first block lands