Allow for curbing logs while testing

**Is your feature request related to a problem? Please describe.**
Yes, I am writing tests for my graphene app. I need to test whether certain queries produce errors. When `client.execute(...)`is run, this logs an annoying `graphql.error.located_error.GraphQLLocatedError`. I cannot even use `pytest.raises` or `self.assertRaises` in unittest because it only logs without actually raising an error. It even logs the entire traceback which is even more annoying.

**Describe the solution you'd like**
It'd be much better if we had a solution to have a loglevel flag in `client.execute(...)` or some other way to disable logging of those specific errors.

**Describe alternatives you've considered**
I have considered disabling all error logs from the test runner (with `logging.disable(logging.ERROR)`). I am going with this for now but I don't want to miss out on other important logs which may help in surfacing faulty tests.

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