Drowns only spawn in deep water

Drowns were intended to be deep monsters of the sea; however in current gameplay, they serve as annoying pests who spawn in small streams of water with tridents with massive range, thereby forcing the player to essentially remove or transform natural water features of the landscape even while building on land.

Instead, drowns should be mobs who should be encountered when the player goes in the water. To do this, ensure that drowns spawn only in water deeper than small rivers, etc.