[DDC-2110] fixed problem with existing table columns (postgresql)
removed unnecessary select
new tests for PostgreSqlPlatform

- added test for getListTableColumnsSQL
- added test for getListTableForeignKeysSQL
- added test for getListTableIndexesSQL
[DBAL-510] Fix tests (remove SQL ones, add functional test.
Merge branch 'DBAL-510' into 2.3