Source-postgres: align regular and CDC integration tests and data mappers

[etsybaev]

Currently, we have 2 different classes for integration datatype tests CdcPostgresSourceDatatypeTest and PostgresSourceDatatypeTest.

1. Merge them. Implement timezone-aware data types instead of strings for schema type. Make a base class and add the possibility to run it using different configurations (ex. by subclasses where you add config). See SSH (key or login]pass) as an example
2. update data mappers. Most probably that in some tests for common and CDC sync will have a different expected result. So additional work would be required to alignn it.