Since the configs were mainly to control UI pref (which is not usable
with user.js, as it will always override manual customization)
The rest of the features provided by user.js isn't necessary and are
already covered by policies.

So for now, I'm removing this user.js integration, maybe revisit it
later if it's proven to be useful, ATM, it complicates and brittles the
setup without providing any additional value.

And fix the role ideompotent testing

To avoid potential conflict when a user already have a profile named and
configured for them, it's simpler to use a defined ansible profile that
also indicates that the profile is automated

The USER env is failing on CI, so reverting back to using ansible_user_id
special variable, the ansible_user also failed as the CI doesn't have
ssh connection (at least not during the tests, and therefore the
ansible_user is undefined)