Use `disable_footer` variable to disable footer on login page

Rather than Mako block hack

lms/djangoapps/student_account/views.py

@@ -116,6 +116,7 @@ def login_and_registration_form(request, initial_mode="login"):
         'responsive': True,
         'allow_iframing': True,
         'disable_courseware_js': True,
+        'disable_footer': True,
     }
 
     return render_to_response('student_account/login_and_register.html', context)

lms/templates/student_account/login_and_register.html

@@ -27,10 +27,3 @@
 <div class="section-bkg-wrapper">
     <div id="login-and-registration-container" class="login-register" />
 </div>
-
-% if settings.FEATURES.get('ENABLE_COMBINED_LOGIN_REGISTRATION'):
-    ## This overwrites the "footer" block declared in main.html
-    ## with an empty block, effectively hiding the footer
-    ## from logistration pages.
-    <%block name="footer"/>
-% endif