Fix 3DBall and 3DBallHard SAC regressions (#4132)

config/sac/3DBall.yaml

       learning_rate: 0.0003
       learning_rate_schedule: constant
       batch_size: 64
-      buffer_size: 12000
+      buffer_size: 200000
       buffer_init_steps: 0
       tau: 0.005
       steps_per_update: 10.0
         gamma: 0.99
         strength: 1.0
     keep_checkpoints: 5
-    max_steps: 500000
+    max_steps: 200000
     time_horizon: 1000
     summary_freq: 12000
     threaded: true

config/sac/3DBallHard.yaml

       learning_rate: 0.0003
       learning_rate_schedule: constant
       batch_size: 256
-      buffer_size: 50000
+      buffer_size: 500000
       buffer_init_steps: 0
       tau: 0.005
       steps_per_update: 10.0