Remove last vestiges of Studio collapsing

openassessment/templates/openassessmentblock/edit/oa_edit_criterion.html

 {% load i18n %}
 {% spaceless %}
-<li class="openassessment_criterion is-collapsible" data-criterion="{{ criterion_name }}">
+<li class="openassessment_criterion" data-criterion="{{ criterion_name }}">
     <div class="openassessment_container_header openassessment_criterion_header view-outline">
-        <a class="action expand-collapse collapse"></a>
         <div class="openassessment_container_header_title_box openassessment_criterion_header_title_box">
             <h6 class="openassessment_container_header_title openassessment_criterion_header_title">{% trans "Criterion" %}</h6>
             <p class="openassessment_container_guide openassessment_criterion_guide">{% trans "You cannot delete a criterion after the assignment has been released." %}</p>

openassessment/templates/openassessmentblock/edit/oa_edit_prompt.html

 {% load i18n %}
 {% spaceless %}
-<li class="openassessment_prompt is-collapsible" data-prompt="{{ prompt_uuid }}">
+<li class="openassessment_prompt" data-prompt="{{ prompt_uuid }}">
 
     <div class="openassessment_container_header openassessment_prompt_header view-outline">
-        <a class="action expand-collapse collapse"></a>
         <div class="openassessment_container_header_title_box openassessment_prompt_header_title_box">
             <h6 class="openassessment_container_header_title openassessment_prompt_header_title">{% trans "Prompt" %}</h6>
             <p class="openassessment_container_guide openassessment_prompt_guide">{% trans "You cannot delete a prompt after the assignment has been released." %}</p>

openassessment/templates/openassessmentblock/edit/oa_training_example.html

 {% load i18n %}
 {% spaceless %}
-<li class="openassessment_training_example is-collapsible">
+<li class="openassessment_training_example">
 
     <div class="openassessment_training_example_header view-outline">
-        <a class="action expand-collapse collapse"></a>
         <h6 class="openassessment_training_example_header_title">
             {% trans "Scored Response" %}
         </h6>