Improve stability of update process

[lonvia]

Updates currently submit all data in one single bulk request to the ES/OS database. This can become too much data when updates are done for a larger time span. We should be sending data to the database in 10k bulks just like the import does.

Related to this: the TODO list in the Nominatim table is deleted immediately when items are read. This means that it is possible that objects get lost when the process is interrupted for some reason before the places are written in to the ES/OS database. Proper use of transactions should avoid that.