Implement partial parsing for singular data tests configs in yaml files

[gshank]

Resolves #10801

Problem

Changes to singular data test configs in yaml files were not causing the singular data test nodes to be updated.

Solution

Add partial parsing code to handle data_tests sections in schema source files.

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

Attention: Patch coverage is 94.11765% with 1 line in your changes missing coverage. Please review.

Project coverage is 89.16%. Comparing base (fdfe03d) to head (6938208).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #11100      +/-   ##
==========================================
- Coverage   89.17%   89.16%   -0.01%     
==========================================
  Files         183      183              
  Lines       23783    23799      +16     
==========================================
+ Hits        21209    21221      +12     
- Misses       2574     2578       +4     

Flag	Coverage Δ
integration	86.54% <94.11%> (-0.03%)	⬇️
unit	62.17% <5.88%> (+<0.01%)	⬆️

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

Components	Coverage Δ
Unit Tests	62.17% <5.88%> (+<0.01%)	⬆️
Integration Tests	86.54% <94.11%> (-0.03%)	⬇️