JDBC KType mismatches in "debug" mode

[Jolanrensen]

Related to #713

Running the JDBC tests with kotlin.dataframe.debug=true results in 15 failing tests:

• SqliteTest
  • read from all tables
  • read from sql query
  • read from tables
• JdbcTest
  • read from huge table
• MSSQLH2Test
  • read from all tables
  • basic test for reading sql tables
• MariadbH2Test
  • read from all tables
  • basic test for reading sql tables
  • reading numeric types
• MySqlH2Test
  • read from all tables
  • basic test for reading sql tables
  • reading numeric types
• PostgresH2Test
  • read from all tables
  • read from tables
  • read columns of different types to check type mapping