End gateway exit portals can be set to high coordinates, kicking the player

The bug

The exit portal of an end gateway can be set to high coordinates (30,000,000 or more), which kicks the player. This causes MC-123587, and can be used as a method to prevent a player from joining a server once they enter the gateway.

How to reproduce

1. Run the command:

   /setblock ~ ~-1 ~1 minecraft:end_gateway{Age:180,ExactTeleport:1,ExitPortal:{X:0,Y:50000000,Z:0}}

   Kicked (MC-123587)