fix zombie mispredicts (#11043)

Content.Shared/Zombies/SharedZombieSystem.cs

@@ -0,0 +1,20 @@
+using Content.Shared.Movement.Systems;
+
+namespace Content.Shared.Zombies;
+
+public abstract class SharedZombieSystem : EntitySystem
+{
+    /// <inheritdoc/>
+    public override void Initialize()
+    {
+        base.Initialize();
+
+        SubscribeLocalEvent<ZombieComponent, RefreshMovementSpeedModifiersEvent>(OnRefreshSpeed);
+    }
+
+    private void OnRefreshSpeed(EntityUid uid, ZombieComponent component, RefreshMovementSpeedModifiersEvent args)
+    {
+        var mod = component.ZombieMovementSpeedDebuff;
+        args.ModifySpeed(mod, mod);
+    }
+}