[datafeed] do NOT call commit in DataFeedXMLParser.process() (closes #10928592) and so, remove more useless code. Doing a commit in DataFeedXMLParser.process() is a bad idea because this method is called for every imported/updated entity, before handling deletions. So if we commit here, odds are quite high that we're violating some integrity constraint and end up with a ValidationError.

[system]
db-driver   = sqlite
db-name     = tmpdb-extern
db-encoding = UTF-8