Ender Dragon is respawned if all Exit End Portal blocks are removed / legacy scanning is done for worlds with new dragon fight

The underlying issue is that legacy scanning happens every time even if a DragonFight NBT compound already exists.

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If you kill the Ender Dragon in the end and then remove all the end portal frames from the portal, then relog, you will see a new bossbar for a new Ender Dragon. You can't target it with @e as it doesn't actually exist yet, but it will spawn when you move far enough from 0 0. Basically this means that a new dragon always spawns if the frames are removed, even if you never placed the end crystals right. This limits what creative players can do in the end, as there's always a portal located (and a dragon, if the portal got removed)

How to reproduce

1. Open a creative world
2. Go to the end dimension and defeat the Ender Dragon
3. Break all the the end portal blocks
4. Break all end gateways
5. Exit the world and reload it
   You should see the Exit End Portal go back to how it was before the Ender Dragon was killed and the Ender Dragon's health bar appear at the top of the screen. Wait about a minute and the Ender Dragon will respawn.