We need to mock the calls to `salt.client.get_local_client` in the
tests.unit.test_auth.py file. Without these mocks, there are many tests
that fail when the entire set of unit tests runs. (Specifically, these fail
with both the module and state boto_apigateway unit tests run.)
This mocked patch is similar to the change in PR #41082 and fixes all 16 test
failures reported in https://github.com/saltstack/salt-jenkins/issues/326.
