New workflow for creating public pm20 endpoint

[jneubert]

Loading of the JSON-LD files created in the Wikitech environment into an empty Fuseki/TDB database. Since repeated "drop graph" operations result in errors, this has to be done by deletion and reinitialization of the database directory (requires sudo).

Initiated from pm20.zbw.eu.

Remove rebuild_all_data.sh and recreate_pm20_endpoint.sh, which are replaced by the new workflow (these files were copied over from ite-srv24, but were never functional on pm20.zbw.eu).