delete tests taht should be in core

[McKnight-42]

resolves #
docs dbt-labs/docs.getdbt.com/#

Problem

when we first pulled dbt-postgres out we brought a lot of tests that really belong in core over, we are moving them back out as we find them

Solution

delete test files as needed

Checklist

• I have read the contributing guide and understand what's expected of me
• I have run this code in development and it appears to resolve the stated issue
• This PR includes tests, or tests are not required/relevant for this PR
• This PR has no interface changes (e.g. macros, cli, logs, json artifacts, config files, adapter interface, etc) or this PR has already received feedback and approval from Product or DX