Stop gitolite mirroring for translation repo

Ey there:

As we move to weblate, and weblate has nice integration with gitlab, we should finish the move out of gitolite.

At the moment, the setup is:

• the server majus (administered by the l10n coordinator) asks changes to transifex with their propietary client, and sends commits to ssh://git@git-rw.torproject.org/translation.git
• gitolite-merge-bot mirrors the repo to https://gitlab.torproject.org/tpo/translation
• developers can hook their builds either to git.tpo or gitlab.tpo (they used to only have gitolite, so we need to make sure they have changed to the gitlab repo)

the new setup should be:

• weblate slowly replaces majus on sending said commits, but to https://gitlab.torproject.org/tpo/translation
• developers hook their builds to https://gitlab.torproject.org/tpo/translation
• gitolite-merge-bot and majus will not be needed anymore

it seems majus will not be needed because weblate provides its own repository (a difference with transifex).

task list:

• make majus talk with gitlab instead of gitolite (@emmapeel)
• stop mirroring between gitolite and gitlab for the translation.git repo (@anarcat)
• archive the translation.git repo? (@anarcat)