resolves #210
resolves #208

Problem

While working on dbt-labs/dbt-core#10075, I noticed a few things about this test case:

1. The date range is larger than needed
2. The test can give a false positives
3. There are hard-coded adapter types

The second one is the most impactful. This PR solves the first two.

Solution

1. Reduce the date range from 9 down to 3 (which gets rid of 36 lines of code)
2. Use a full outer join rather than a left join to eliminate possibility of a false positive

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
• New 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.)