Fixed Errors in Experimental MaterializedPostgreSQL Engine

Fixed error on generated columns in the experimental and totally unsupported MaterializedPostgreSQL engine when adnum ordering is broken #63161. Fixed error on id column with nextval expression as default in the experimental and totally unsupported MaterializedPostgreSQL when there are generated columns in table. Fixed error on dropping publication with symbols except [a-z1-9-]. #67664 (Kruglov Kirill).