When a customer cancels a loan application before we even pull credit is an adverse action notice needed?

I would say it is a withdrawn application.

The bank did not take " Action that was Adverse to the Applicant" = No notice required

As long as you did not communicate any adverse action to the borrower, than no notice is required. But, for example, if you had an application and you looked at it and said you won't qualify based on your income or some other type of information in the application, you would need to send an adverse action under Regulation B.