Update templates and profiles for the new images urls

This commit updates all the test templates and profiles for the new
images urls. It includes the following changes:

- Add two new optional variables opt_image_type/opt_board and check
if they are defined before using them as a work-around for the amd64
wayland image url.
- Move some common profiles variables to the parent profile.
- Include the new minnowboard-max-minimal profile.