Shift swarmer shoot barrels to match the chutes (#8624)

Similar to how cyclone shoot barrels match the ends of each barrel.

core/src/mindustry/content/Blocks.java

@@ -3414,10 +3414,13 @@ public class Blocks{
                 }}
             );
             
-            shoot = new ShootAlternate(){{
+            shoot = new ShootBarrel(){{
+                barrels = new float[]{
+                    -4, -1.25f, 0,
+                    0, 0, 0,
+                    4, -1.25f, 0
+                };
                 shots = 4;
-                barrels = 3;
-                spread = 3.5f;
                 shotDelay = 5f;
             }};