chore: remove always-true check from insert_with_markers()

Author: justlevine

src/wp-admin/includes/misc.php

@@ -205,7 +205,7 @@ function insert_with_markers( $filename, $marker, $insertion ) {
 
 		if ( ! $found_marker ) {
 			$pre_lines[] = $line;
-		} elseif ( $found_marker && $found_end_marker ) {
+		} elseif ( $found_end_marker ) {
 			$post_lines[] = $line;
 		} else {
 			$existing_lines[] = $line;