We named these jobs like this despite b2c being an implementation
detail because we did not have a name for this bare-metal infra.
Now that we do (CI-Tron), let's rename the jobs to remove the
confusion.
Co-authored-by: Eric Engestrom <eric@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34795>