remove extra way to attach to discussion

fixes CNVS-29918

Test Plan:
- In a course, navigate to the Settings page
- On the Course Details tab, click on the "more options" link at the bottom of the page
- Make sure that the "Let students attach files to discussions" option is checked
- Navigate to a discussion in the course
- Begin creating a new reply
- Note that there is an "Attach" option in the bottom left
- Post the reply
- Click on the Cog menu on the post and choose "Edit"
- Note that the Attach option is not there

Change-Id: Ib05e14107adeb934b51e60a04f73cc083d5fc520
Reviewed-on: https://gerrit.instructure.com/95678
Tested-by: Jenkins
Reviewed-by: Clay Diffrient <cdiffrient@instructure.com>
QA-Review: David Tan <dtan@instructure.com>
Product-Review: Steven Burnett <sburnett@instructure.com>

Author: sdb1228

app/views/jst/discussions/_reply_form.handlebars

@@ -29,14 +29,6 @@
               id="{{#if root}}root_{{/if}}reply_message_for_{{id}}"></textarea>
 
     <div class="clearfix">
-      <div class="discussion-reply-attachments-container">
-        <ul class="discussion-reply-attachments"></ul>
-        {{#if canAttach}}
-          <a href="#" class="discussion-reply-add-attachment discussion-reply-action icon-paperclip"
-             data-event="addReplyAttachment">{{#t "attach_file"}}Attach{{/t}}</a>
-        {{/if}}
-      </div>
-
       <div class="discussion-reply-buttons">
         <a href="javascript:" class="cancel_button btn btn-small">{{#t "cancel"}}Cancel{{/t}}</a>
         <button class="btn btn-primary btn-small" type="submit">{{#t "post_reply"}}Post Reply{{/t}}</button>

spec/selenium/helpers/discussions_common.rb

@@ -64,9 +64,10 @@ def add_reply(message = 'message!', attachment = nil)
 
     if attachment.present?
       filename, fullpath, data = get_file(attachment)
-      @last_entry.find_element(:css, '.discussion-reply-add-attachment').click
+      f('#ui-id-2').click
       wait_for_ajaximations
-      @last_entry.find_element(:css, '.discussion-reply-attachments input').send_keys(fullpath)
+      f('#editor_tabs_3 > div:nth-child(3) > a').click
+      f('#attachment_uploaded_data').send_keys(fullpath)
     end
 
     submit_form(@last_entry.find_element(:css, ".discussion-reply-form"))