BUG Removed 'Sort' field from CMSMain edit form

Related to #7740. The sort field gets stale if the current
record is moved in the tree. Since the sort value can't
be altered by interacting with the form, its not required
as a hidden field, either.

code/controllers/CMSMain.php

@@ -578,8 +578,6 @@ class CMSMain extends LeftAndMain implements CurrentPageIdentifier, PermissionPr
 			$fields->push($stageLinkField = new HiddenField("StageLink"));
 			$fields->push(new HiddenField("TreeTitle", false, $record->TreeTitle));
 
-			$fields->push(new HiddenField('Sort','', $record->Sort));
-
 			if($record->ID && is_numeric( $record->ID ) ) {
 				$liveLink = $record->getAbsoluteLiveLink();
 				if($liveLink) $liveLinkField->setValue($liveLink);