This test did not work when splitting the metadata and source backends. Fixed mostly by running the relevant SQL using `source_backend.engine`, but I also took the time to clean it up a little, and broke up _test.yaml_ into 3 files.
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/6957
GitOrigin-RevId: bbca60a8906caba2d0cffd834b3b8595fca058fd