[gantry][tests] Handler warning better from docker command. Do not us… #866

Job	Run time
shellcheck	9s
Test container	3m 1s
Test scripts (gantry_cleanup_images_spec.sh)	1m 7s
Test scripts (gantry_common_options_spec.sh)	1m 6s
Test scripts (gantry_filters_spec.sh)	53s
Test scripts (gantry_jobs_spec.sh)	48s
Test scripts (gantry_login_docker_config_spec.sh)	52s
Test scripts (gantry_login_negative_spec.sh)	1m 12s
Test scripts (gantry_login_spec.sh)	1m 5s
Test scripts (gantry_manifest_spec.sh)	54s
Test scripts (gantry_notify_spec.sh)	1m 28s
Test scripts (gantry_parallel_spec.sh)	1m 10s
Test scripts (gantry_rollback_spec.sh)	54s
Test scripts (gantry_service_multiple_spec.sh)	28s
Test scripts (gantry_service_no_running_tasks_spec.sh)	59s
Test scripts (gantry_service_single_spec.sh)	47s
Test scripts (gantry_update_options_spec.sh)	1m 8s
Build and push Docker image	0s
	18m 1s

Provide feedback