Fix EntityTeleportEvent triggering twice

[orang3i]

fixes #12317

fix vanilla tp command firing the EntityTeleportEvent twice and CraftEntity#teleport firing the EntityTeleportEvent twice for cross world teleports.

[orang3i]

• for CraftEntity#teleport the event is called twice only for cross world teleports. This was fixed by adding a check before the event call in CraftEntity#teleport to check if the destination and current location are of the same worlds and if they are, we don't call the event and the event is fired from vanilla teleport.

edit : Now it also works for null world teleports

• for vanilla tp command class, the event call is entirely removed and the event will be called from vanilla teleport.

[orang3i]

This pr only fixes the vanilla tp command firing the EntityTeleportEvent twice.

Edit : fixes both issues in #12317

[orang3i]

Update: Fixed the boolean check to also trigger event and allow teleport for null worlds in CraftEntity#teleport and prevents double triggering of event in cross world teleports

[Warriorrrr]

Thank you for your contribution and apologies for the delay, we're currently planning on going ahead with the changes #13181 soon which is a larger rework of the teleport implementation, which also happens to fix both of these issues, so I think it's best if that PR supersedes this one.