Update to nether fortress spawning mechanics for fortress mobs

Dear Mojang here are some things i as a long time Minecraft player am still bothered by or desire to see in the game to this day, Nether fortress spawn cap slots being consumed by non nether fortress mobs makes getting wither skulls unnecessarily difficult and tedious ESPECIALLY to those who are not aware of how to manipulate the spawning mechanics to increase their odds of skulls per minute i believe tweaks to nether fortresses spawning mechanics would be much appreciated by the community at large hopefully a solution that can be implemented without affecting existing creations and not require too much work to implement. perhaps we can give the bounds of a nether fortress its own separate mob cap for fortress mobs? seems like a sensible solution to me or maybe a check that when a fortress table mob attempts to spawn it can despawn an out of sight / further away "normal" mob.

i think this change would be great for the game as adventure and mystique has been a theme lately and 1.21 i think this would be a great time to implement such a subtle fix maybe we can even add new loot filled decorative pots to old structures with matching sherds decorating them albeit rare to find or maybe in new secret rooms...