Allow customization of postgres login_db and maintenance_db in ansible tasks

As a User of the GET I want to be able to use the ansible code on Cloud Providers other than the hyper scalers. On these other cloud providers I want to be able to use cloud services for e.g. a managed postgres where I might not have access to the "template1" or the "postgres" database. As the ansible code relies on these databases, I want to be able to customize the database used for the tasks using ansible vars.