[tests] update checks for ADDING_OPTIONS. fix using subprocess variab… #393

Job	Run time
shellcheck	13s
Test script (gantry_cleanup_images_spec.sh)	1m 56s
Test script (gantry_common_options_spec.sh)	1m 26s
Test script (gantry_filters_spec.sh)	1m 11s
Test script (gantry_login_spec.sh)	1m 52s
Test script (gantry_manifest_spec.sh)	1m 39s
Test script (gantry_notify_spec.sh)	1m 27s
Test script (gantry_parallel_spec.sh)	2m 13s
Test script (gantry_rollback_spec.sh)	1m 7s
Test script (gantry_service_multiple_spec.sh)	1m 54s
Test script (gantry_service_no_running_tasks_spec.sh)	1m 27s
Test script (gantry_service_single_spec.sh)	1m 23s
Test script (gantry_update_options_spec.sh)	1m 50s
Build and push Docker image	1m 4s
Test container	2m 24s
	23m 6s

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