Fix order of activities with same timestamp

When activities of the same type have the same timestamp, for example
when created from cloning issues, use the element id for sorting.

Fixes: #22441

core/bug_activity_api.php

@@ -187,6 +187,11 @@ function bug_activity_sort( &$p_entries ) {
 			return $t_order == 'DESC' ? -1 : 1;
 		}
 
+		# same timestamp and same type, probably came from cloning an issue
+		if( $a['timestamp'] == $b['timestamp'] && $a['type'] == $b['type'] ) {
+			return (int)$a['id'] - (int)$b['id'];
+		}
+
 		if( $a['user_id'] < $b['user_id'] ) {
 			return -1;
 		}