chore(bigquery): remove duplicate test dependencies (#9503)
chore(bigquery): remove duplicate test dependencies (#9503)

* chore(bigquery): remove duplicate test dependencies

* Demote test_utils from LOCAL_DEPS in noxfile

The test_utils dependency is only nedeed for test sessions, but not
for some other nox sessions such as "lint" and "docs".

tseaver/google-cloud-python,GoogleCloudPlatform/gcloud-python,tswast/google-cloud-python,googleapis/google-cloud-python,tseaver/google-cloud-python,googleapis/google-cloud-python,GoogleCloudPlatform/gcloud-python,tswast/google-cloud-python,tseaver/google-cloud-python,tswast/google-cloud-python