MDL-47476 qformat_learnwise: rest in peace.

Learnwise was an old LMS that no longer exists. (Last reference found on
Google from 2009.) So we are removing the ability to import questions in
that format.

lib/classes/plugin_manager.php

@@ -910,7 +910,7 @@ class core_plugin_manager {
         // branch, listed should be no plugins that were removed at 1.9.x - 2.1.x versions as
         // Moodle 2.3 supports upgrades from 2.2.x only.
         $plugins = array(
-            'qformat' => array('blackboard'),
+            'qformat' => array('blackboard', 'learnwise'),
             'enrol' => array('authorize'),
             'tinymce' => array('dragmath'),
             'tool' => array('bloglevelupgrade', 'qeupgradehelper'),
@@ -1086,7 +1086,7 @@ class core_plugin_manager {
 
             'qformat' => array(
                 'aiken', 'blackboard_six', 'examview', 'gift',
-                'learnwise', 'missingword', 'multianswer', 'webct',
+                'missingword', 'multianswer', 'webct',
                 'xhtml', 'xml'
             ),