Fish, Sheep and Yak no longer spawn in HTTYD due to a unversioned spawn rule change

Partner Rank: 2. Normal

Partner Team Reporting: Gamemode One

Verification builds: 1.19.41.01_rc0 & Up (R19U5, R19U6, R19U7)
Summary: 
A change was made to spawn rules which was unversioned and not noted in a changelog which prevents Fish, Yaks, and Sheep from spawning in How To Train Your Dragon. All three creatures now need the `"minecraft:spawns_underground": {},` condition in the spawn rule despite not being underground.
Impact:

Gameplay can be soft-locked (unable to tame some creatures) until a patch is released to add the `"minecraft:spawns_underground": {},` condition. 

Repro Steps:

1. Play on retail (R/19U7H3)
2. Download HTTYD from the store
3. Create a world from template
4. Enter creative and fly around, observe no fish in the sea and no yaks / sheep on land
5. Install `1.19.40.02_RC1` 
6. Repeat steps 2-3
7. Observe fish, sheep and yak spawning
8. Return to retail
9. Add the `"minecraft:spawns_underground": {},`  condition
10. Load world
11. Observe fish, sheep and yak spawning

Observed Results:

Fish no longer spawn in the sea unless they are given the `"minecraft:spawns_underground"` condition in their spawn rule.

Yak and sheep no longer spawn on the surface unless they are given the ``"minecraft:spawns_underground"` condition in their spawn rule.

 

Expected Results:

Fish, Sheep, and Yaks spawn within the sea / on land where their spawn rule conditions are met. The ``"minecraft:spawns_underground"` condition is not needed for creatures which are not under the ground.

OR

Changes to spawn rules are noted in a changelog to allow creators to update content.

OR
Changes to spawn rules are a versioned change in the engine.

Regression Builds:

1.19.40.02_RC1

Screenshots/Videos attached: Yes

Notes: A build with the changes made to add the spawn condition can be provided.{}