Delete mention of direction from checkboxgroup.

It was never implemented.
TNL-231

common/test/acceptance/tests/data/multiple_choice.xml

@@ -17,7 +17,7 @@
   </multiplechoiceresponse>
   <p>Which of the following are musical instruments?</p>
   <choiceresponse>
-    <checkboxgroup direction="vertical">
+    <checkboxgroup>
       <choice correct="true">a piano</choice>
       <choice correct="false">a tree</choice>
       <choice correct="true">a guitar</choice>

common/test/acceptance/tests/lms/test_lms_user_preview.py

@@ -62,7 +62,7 @@ class CourseWithoutContentGroupsTest(StaffViewTest):
             <problem markdown="Simple Problem" max_attempts="" weight="">
               <p>Choose Yes.</p>
               <choiceresponse>
-                <checkboxgroup direction="vertical">
+                <checkboxgroup>
                   <choice correct="true">Yes</choice>
                 </checkboxgroup>
               </choiceresponse>
@@ -258,7 +258,7 @@ class CourseWithContentGroupsTest(StaffViewTest):
             <problem markdown="Simple Problem" max_attempts="" weight="">
               <p>Choose Yes.</p>
               <choiceresponse>
-                <checkboxgroup direction="vertical">
+                <checkboxgroup>
                   <choice correct="true">Yes</choice>
                 </checkboxgroup>
               </choiceresponse>

common/test/acceptance/tests/studio/test_studio_settings.py

@@ -136,7 +136,7 @@ class ContentGroupConfigurationTest(StudioCourseTest):
             <problem markdown="Simple Problem" max_attempts="" weight="">
               <p>Choose Yes.</p>
               <choiceresponse>
-                <checkboxgroup direction="vertical">
+                <checkboxgroup>
                   <choice correct="true">Yes</choice>
                 </checkboxgroup>
               </choiceresponse>

common/test/data/manual-testing-complete/problem/a473cecce312487a8339995bde24be53.xml

@@ -2,7 +2,7 @@
   <p>A checkboxes problem presents checkbox buttons for student input. Students can select more than one option presented.</p>
   <p>Select the answer that matches</p>
   <choiceresponse>
-    <checkboxgroup direction="vertical" label="Select the answer that matches">
+    <checkboxgroup label="Select the answer that matches">
       <choice correct="true">correct</choice>
       <choice correct="false">incorrect</choice>
       <choice correct="true">correct</choice>

common/test/data/manual-testing-complete/problem/dcada38f8944442799ac2fed42201641.xml

@@ -2,7 +2,7 @@
   <p>A checkboxes problem presents checkbox buttons for student input. Students can select more than one option presented.</p>
   <p>Select the answer that matches</p>
   <choiceresponse>
-    <checkboxgroup direction="vertical" label="Select the answer that matches">
+    <checkboxgroup label="Select the answer that matches">
       <choice correct="true">correct</choice>
       <choice correct="false">incorrect</choice>
       <choice correct="true">correct</choice>