Fixed concurrency issues with DDL operations in Atomic database engine

Fixed DROP TABLE IF EXISTS failure with Table ... does not exist error when table is concurrently renamed (for Atomic database engine). Fixed rare deadlock when concurrently executing some DDL queries with multiple tables (like DROP DATABASE and RENAME TABLE) Fixed DROP/DETACH DATABASE failure with Table ... does not exist when concurrently executing DROP/DETACH TABLE. #15934 (tavplubix).