[lib-common] increase docker log speed. #764

Job	Run time
shellcheck	8s
Test script (gantry_cleanup_images_spec.sh)	59s
Test script (gantry_common_options_spec.sh)	1m 17s
Test script (gantry_filters_spec.sh)	57s
Test script (gantry_jobs_spec.sh)	1m 0s
Test script (gantry_login_docker_config_spec.sh)	57s
Test script (gantry_login_negative_spec.sh)	59s
Test script (gantry_login_spec.sh)	1m 16s
Test script (gantry_manifest_spec.sh)	59s
Test script (gantry_notify_spec.sh)	1m 17s
Test script (gantry_parallel_spec.sh)	59s
Test script (gantry_rollback_spec.sh)	43s
Test script (gantry_service_multiple_spec.sh)	35s
Test script (gantry_service_no_running_tasks_spec.sh)	53s
Test script (gantry_service_single_spec.sh)	59s
Test script (gantry_update_options_spec.sh)	59s
Build and push Docker image	1m 2s
Test container	2m 19s
	18m 18s

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