[TECH DEBT] Create a fixture to read a dashboard query within a test

[aminmovahed-db]

Maybe we want to implement a fixture to get the query to make sure we test that, something like:

1. query = get_query("04_1_....sql")
2. Replace database
3. Run query
4. Verify results

Originally posted by @JCZuurmond in databrickslabs/ucx#2205 (comment)