Poppies and dandelions can generate in old growth pine taiga biomes

In old growth pine taiga biomes, poppies and dandelions are able to generate, which looks unnatural considering their environment.

Steps to Reproduce:

1. Generate a single biome world, set to Old Growth Pine Tiaga
2. Fly around until you find poppies or dandelions

Observed Behavior:

Poppies and dandelions can generate in old growth pine taiga biomes.

Expected Result:

Poppies and dandelions would not be able to generate in old growth pine taiga biomes.

Notes:

Related to other decoration oriented issues:
MC-140727 MC-226027 MC-140242 MC-256102 MC-218726 MC-244203 MC-238711