Evaluate and replace the use of "Install selected language pack(s)" in behat

After dobedobedoh patch's on MDL-77037, it would be great to retrofit the new step into some of the tests using "Install selected language pack(s)", when it is used as a setup step.

We should instead use the new step:

And the following "language pack" exists:
| language | xxx |

Main examples:

• calendar/tests/behat/calendar_utf8.feature (used to check the calendar behaviour)
• auth/tests/behat/loginform.feature
• theme/boost/tests/behat/languagemenu.feature

Pinging lameze