set Agent.maxSteps for FoodCollector prefabs (#3416)

Project/Assets/ML-Agents/Examples/FoodCollector/Prefabs/FoodCollectorArea.prefab

   m_Script: {fileID: 11500000, guid: c66e6845309d241c78a6d77ee2567928, type: 3}
   m_Name: 
   m_EditorClassIdentifier: 
-  maxStep: 0
+  maxStep: 5000
   area: {fileID: 1819751139121548}
   turnSpeed: 300
   moveSpeed: 2
   m_Script: {fileID: 11500000, guid: c66e6845309d241c78a6d77ee2567928, type: 3}
   m_Name: 
   m_EditorClassIdentifier: 
-  maxStep: 0
+  maxStep: 5000
   area: {fileID: 1819751139121548}
   turnSpeed: 300
   moveSpeed: 2
   m_Script: {fileID: 11500000, guid: c66e6845309d241c78a6d77ee2567928, type: 3}
   m_Name: 
   m_EditorClassIdentifier: 
-  maxStep: 0
+  maxStep: 5000
   area: {fileID: 1819751139121548}
   turnSpeed: 300
   moveSpeed: 2
   m_Script: {fileID: 11500000, guid: c66e6845309d241c78a6d77ee2567928, type: 3}
   m_Name: 
   m_EditorClassIdentifier: 
-  maxStep: 0
+  maxStep: 5000
   area: {fileID: 1819751139121548}
   turnSpeed: 300
   moveSpeed: 2

Project/Assets/ML-Agents/Examples/FoodCollector/Prefabs/VisualFoodCollectorArea.prefab

   m_Script: {fileID: 11500000, guid: c66e6845309d241c78a6d77ee2567928, type: 3}
   m_Name: 
   m_EditorClassIdentifier: 
-  maxStep: 0
+  maxStep: 5000
   area: {fileID: 1145096862361766}
   turnSpeed: 300
   moveSpeed: 2
   m_Script: {fileID: 11500000, guid: c66e6845309d241c78a6d77ee2567928, type: 3}
   m_Name: 
   m_EditorClassIdentifier: 
-  maxStep: 0
+  maxStep: 5000
   area: {fileID: 1145096862361766}
   turnSpeed: 300
   moveSpeed: 2
   m_Script: {fileID: 11500000, guid: c66e6845309d241c78a6d77ee2567928, type: 3}
   m_Name: 
   m_EditorClassIdentifier: 
-  maxStep: 0
+  maxStep: 5000
   area: {fileID: 1145096862361766}
   turnSpeed: 300
   moveSpeed: 2