Fixed race condition between inserts and materialized view drops in ClickHouse

Fixed (logical) race condition between inserts and dropping materialized views. A race condition happened when a Materialized View was dropped at the same time as an INSERT, where the MVs were present as a dependency of the insert at the begining of the execution, but the table has been dropped by the time the insert chain tries to access it, producing either an UNKNOWN_TABLE or TABLE_IS_DROPPED exception, and stopping the insertion. After this change, we avoid these exceptions and just continue with the insert if the dependency is gone. #43161 (AlfVII).