when merging data speed data into the ender dragon it does not affect the ender dragons speed.

Steps to reproduce.

1. Load up a new world with cheats enabled with creative.
2. run the command /execute in minecraft:the_end run tp @p 0 200 0
3. observe the ender dragons speed
4. run /data merge entity @e[type=minecraft:ender_dragon,distance=..100,limit=1] {Attributes:[ {Base:5,Name:"generic.movement_speed"}

   ]}

5. observe the ender dragons speed.
6. run /summon minecraft:cow
7. run /data merge entity @e[type=minecraft:cow,distance=..100,limit=1] {Attributes:[ {Base:5,Name:"generic.movement_speed"}

   ]}

8. Observe cows speed when moving.