Core 9775/respect sql header in tests

[VersusFacit]

Addresses part of #9775

Problem

We're not respect sql header.

Solution

I'm not a core dev so you may have a better solution in mind. I used some free cycles to upcycle some community code and will also do a followon for dbt bigquery of this feature.

Data tests in general will need support that I don't right now have the expertise to do (we can pair up if you like!)

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 or 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.
• This PR includes type annotations for new and modified functions.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.47%. Comparing base (f64a488) to head (1c46fe2).
⚠️ Report is 89 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #11614      +/-   ##
==========================================
+ Coverage   88.81%   89.47%   +0.66%     
==========================================
  Files         197      199       +2     
  Lines       24790    28220    +3430     
==========================================
+ Hits        22016    25249    +3233     
- Misses       2774     2971     +197     

Flag	Coverage Δ
integration	86.96% <100.00%> (+1.15%)	⬆️
unit	65.26% <33.33%> (+2.40%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
Unit Tests	65.26% <33.33%> (+2.40%)	⬆️
Integration Tests	86.96% <100.00%> (+1.15%)	⬆️

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