Fix l10n broken in venvs, stop packaging makebuildserver script

Currently when installing fdroidserver in a venv, data_files (examples and translations) are placed incorrectly:

With a venv in /home/user/venv files end up in e.g. /home/user/venv/home/user/venv/share/doc/fdroidserver/examples/config.yml or /home/user/venv/home/user/venv/share/locale/bo/LC_MESSAGES/fdroidserver.mo (venv path gets duplicated). This breaks localisation.

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makebuildserver requires this repository to be cloned locally. Fixes #1014 (closed).