refactor: remove unrelated function and add input validation #279

Job	Run time
updater-test-args / validate-inputs	9s
cli-integration (ubuntu)	15s
updater-create-pr / validate-inputs	10s
updater-test-args / cancel-previous-run	6s
cli-integration (windows)	1m 16s
updater-create-pr / cancel-previous-run	3s
cli-integration (macos)	1m 33s
updater-test-args / update	10s
updater-create-pr / update	27s
updater-test-outputs	4s
	4m 13s

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