Is your feature request related to a problem or challenge? Please describe what you are trying to do.
I want to reuse some code added by @thinkharderdev in #3769 in a new test I want to write, but it is in a benchmark at the moment.

Describe the solution you'd like
Refactor common code used for testing code into datafusion/test_utils.rs

Hopefully this will:

1. Make it clear that the code is used for testing
2. Make it more discoverable
3. Encourage people to put more common code here

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.