[docs][tests] clarify documents about authentication and filter. Test… #894

Job	Run time
shellcheck	9s
Test container	2m 57s
Test scripts (gantry_cleanup_images_spec.sh)	1m 3s
Test scripts (gantry_common_options_spec.sh)	1m 11s
Test scripts (gantry_filters_spec.sh)	49s
Test scripts (gantry_jobs_spec.sh)	43s
Test scripts (gantry_login_docker_config_spec.sh)	1m 5s
Test scripts (gantry_login_negative_spec.sh)	1m 1s
Test scripts (gantry_login_spec.sh)	1m 5s
Test scripts (gantry_manifest_spec.sh)	1m 5s
Test scripts (gantry_notify_spec.sh)	1m 16s
Test scripts (gantry_parallel_spec.sh)	1m 10s
Test scripts (gantry_rollback_spec.sh)	47s
Test scripts (gantry_service_multiple_spec.sh)	36s
Test scripts (gantry_service_no_running_tasks_spec.sh)	1m 1s
Test scripts (gantry_service_single_spec.sh)	1m 1s
Test scripts (gantry_update_options_spec.sh)	1m 6s
Build and push Docker image	1m 3s
	19m 8s

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