Use, and extend as necessary, happy path fixture for tests/functional/graph_selection/test_graph_selection.py

[QMalcolm]

Housekeeping

• I am a maintainer of dbt-core

Short description

This ticket should build on the work from #10256. Specifically we want to update the tests in tests/functional/graph_selection/test_graph_selection.py to use the the happy path project fixture where relevant. This may require adding to the happy path fixture.

Acceptance criteria

• We use the happy path project fixture for tests in tests/functional/graph_selection/test_graph_selection.py

Context

This would help catch issues like: #8749