Increase 3DBall generalization sampling interval (#3995)

* increase sampling interval to 2000

* bring it up to 5000

config/ppo/3DBall_randomize.yaml

                 gamma: 0.99
 
 parameter_randomization:
-    resampling-interval: 500
+    resampling-interval: 5000
     mass:
         sampler-type: "uniform"
         min_value: 0.5