Enable test_sample_row_count config on tests

[Ryosuke839]

Currently test_sample_row_count can be overridden by var which works globally but not for each model or test.

This PR enables test_sample_row_count config on tests which precedes global setting.

Config would look like:

models:
  - name: some_model
    columns:
      - name: some_column
        data_tests:
          - not_null:
              meta:
                test_sample_row_count: null

Summary by CodeRabbit

• New Features

  • Per-test sample row count override: individual tests can now override the global sample-row-count setting to control how many test-result samples are captured.

• Tests

  • Added integration tests validating override behavior for both unlimited and limited sample retention, ensuring samples are returned as configured and sampling limits are respected.

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