Trial spawners are not affected by the "spawnerBlocksEnabled" game rule

If the game rule “doMobSpawning” is set to false, Trial Spawners will not spawn mobs even if the new "spawnerBlocksEnabled" game rule is set to true.

This is inconsistent with how Monster Spawners work, allowing seperated control of both natural mob spawning and spawner-spawned mobs.

Relates to MC-266487