Remove calendar_for

https://github.com/opf/openproject/pull/6497

app/views/meetings/_form.html.erb

@@ -43,11 +43,11 @@ See doc/COPYRIGHT.md for more details.
     <div class="form--field-container">
       <%= f.text_field :start_date,
             id: 'meeting-form-start-date',
+            class: '-augmented-datepicker',
             required: true,
             size:     10,
             no_label: true,
             container_class: '-xslim' %>
-      <%= calendar_for('meeting-form-start-date') %>
       <label for="meeting-form-start-time" class="hidden-for-sighted">
         <%= Meeting.human_attribute_name(:start_time) %>
         <label lang="en">