Add contact exclusion between iiwa14 links that can't collide.

Those parts of the robot can't self-collide, but the bounding boxes can, so they're not eliminated by broadphase or the first level of midphase.

PiperOrigin-RevId: 590596376
Change-Id: Iaac130359af85fd87ca28889cb32de258db7ffbf

kuka_iiwa_14/iiwa14.xml

@@ -150,6 +150,12 @@
 
   <contact>
     <exclude body1="base" body2="link1"/>
+    <exclude body1="base" body2="link2"/>
+    <exclude body1="base" body2="link3"/>
+    <exclude body1="link1" body2="link3"/>
+    <exclude body1="link3" body2="link5"/>
+    <exclude body1="link4" body2="link7"/>
+    <exclude body1="link5" body2="link7"/>
   </contact>
 
   <actuator>