Switch default Ubuntu stack's Java to AdoptOpenJDK

Description of the feature request

Because of Oracle & Java licensing changes, macOS stack’s java has been switched to AdoptOpenJDK in this PR. https://github.com/bitrise-io/osx-box-bootstrap/pull/141
I think it would be great to also switch it for the Ubuntu stack’s java too.

Use case / for what or how I would use it

Currently we can do it ourself by using our own docker image https://devcenter.bitrise.io/tutorials/docker/use-your-own-docker-image/

But I think it would be great to switch to AdoptOpenJDK because of they new licensing changes. What do you think?