BEHAT: use PHP configuration instead of YAML configuration

[rsanzante]

Behat has pivoted to PHP configurati9oj (configure Behat using PHP methods) instead of YAML configuration.

See https://docs.behat.org/en/latest/user_guide/configuration/yaml_configuration.html

Aljibe should migrate the provided configuration from yaml fiels to PHP configuration.

Behat provides a command to convert YAML conf to PHP condf:

vendor/bin/behat --convert-config

See previous link.