Remove unnecessary fields.

common/lib/xmodule/xmodule/templates/problem/multiplechoice.yaml

@@ -3,8 +3,6 @@ metadata:
     display_name: Multiple Choice
     rerandomize: never
     showanswer: finished
-    weight: ""
-    attempts: ""
     markdown: 
        "A multiple choice problem presents radio buttons for student input. Students can only select a single 
        option presented. Multiple Choice questions have been the subject of many areas of research due to the early