MDL-48269 messageoutput_email: Remove occurrences of hidepicture

message/output/email/classes/output/email_digest.php

@@ -102,7 +102,6 @@ class email_digest implements \renderable, \templatable {
             $group = new \stdClass();
             $group->id = $conversation->groupid;
             $group->picture = $conversation->picture;
-            $group->hidepicture = $conversation->hidepicture;
             $group->courseid = $conversation->courseid;
             $grouppictureurl = $renderer->image_url('g/g1')->out(false); // Default image.
             if ($url = get_group_picture_url($group, $group->courseid, false, true)) {

message/output/email/classes/task/send_email_task.php

@@ -137,7 +137,7 @@ class send_email_task extends scheduled_task {
         // now this will have to do before 3.7 code freeze.
         // See related MDL-63814.
         $sql = "SELECT DISTINCT mc.id, mc.name, c.id as courseid, c.fullname as coursename, g.id as groupid,
-                                g.picture, g.hidepicture
+                                g.picture
                   FROM {message_conversations} mc
                   JOIN {groups} g
                     ON mc.itemid = g.id