Skeleton trap horses can still spawn if the "spawn_monsters" game rule is set to false

MC-89064 was never fully fixed.

Skeleton trap horses can still spawn if "spawn monsters" is set to false.

Steps to reproduce the issue:

• Create a superflat world with gamerule spawn monsters set to false.

• Set the weather to thundering indefinitely

• Use this command: /setblock 5 0 0 repeating_command_block {TrackOutput:0b,auto:1b,Command:"/tp @e[type=minecraft:skeleton_horse] 0 0 0"}

• Then/tick rate 2000 and wait some seconds.

Expected result:

• A skeleton trap would never spawn.

Actual result:

• It does spawn, which causes the spawn monsters game rule to be incomplete, as it controls monsters spawning naturally, and skeleton trap horses spawn naturally, and are monsters.