Rename baby zombie movement config option

This option does not set the absolute speed of the entity as the name
implies. It sets a modifier. The default (vanilla) value of `0.5` sets
the baby zombie to move at 50% faster than the base speed.

A negative value like `-0.4` would set them to move at 40% slower.

There should be no functional changes as a result of this change, it's
just clarifying the config name.

Spigot-Server-Patches/Block-Enderpearl-Travel-Exploit.patch

@@ -12,7 +12,7 @@ This disables that by not saving the thrower when the chunk is unloaded.
 This is mainly useful for survival servers that do not allow freeform teleporting.
 
 diff --git a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
-index 0b6e812d8d..da10550030 100644
+index c57f7e7e8..cb8922329 100644
 --- a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
 +++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
 @@ -0,0 +0,0 @@ public class PaperWorldConfig {
@@ -27,7 +27,7 @@ index 0b6e812d8d..da10550030 100644
 +    }
  }
 diff --git a/src/main/java/net/minecraft/server/EntityProjectile.java b/src/main/java/net/minecraft/server/EntityProjectile.java
-index 5f0cb4c33d..f2f4b2d929 100644
+index 5f0cb4c33..f2f4b2d92 100644
 --- a/src/main/java/net/minecraft/server/EntityProjectile.java
 +++ b/src/main/java/net/minecraft/server/EntityProjectile.java
 @@ -0,0 +0,0 @@ public abstract class EntityProjectile extends Entity implements IProjectile {