Revert 1c884fa4e5a847549afa45350e37b0362c50feae which introduced the
following bug:
Instead of allowing to dump the `ansible-playbook` command details when
VAGRANT_LOG=debug was defined, it was then impossible to disable this
console output when VAGRANT_LOG was undefined (in such case,
``@logger.debug? systematically returns `true`)
In order to keep things simple and focused, it is preferable to drop the
bad idea to mix Ansible verbosity and Vagrant log level.
Fix#5803
839a2e6fa6