rdbms: Pass required parameter

Found by PHPStan.

Change-Id: I8fbb64f7b5058b36381bccd5bc6a9d095b9ace15

includes/libs/rdbms/database/Database.php

@@ -3742,7 +3742,7 @@ abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAware
 				}
 			}
 			if ( $pos < 0 ) {
-				throw new DBUnexpectedError( "Atomic section not found (for $fname)" );
+				throw new DBUnexpectedError( $this, "Atomic section not found (for $fname)" );
 			}
 			// Remove all descendant sections and re-index the array
 			$excisedIds = [];