More cleanup. Remove dashboard.

[heiner]

This is a somewhat sad moment as the dashboard was actually kind of cool and useful. But we haven't been updating it (it doesn't currently work with our ttyrecs) and its causing a maintenance burden.

                       ----------
                      /          \
                     /    REST    \
                    /      IN      \
                   /     PEACE      \
                  /                  \
                  |       N L E      |
                  |     dashboard    |
                  |     killed by    |
                  |      heiner      |
                  |                  |
                  |      * 2019      |
                  |      + 2021      |
                 *|     *  *  *      | *
        _________)/\\_//(\/(/\)/\//\/|_)_______

[cdmatters]

An honourable death.

[heiner]