import_url migration performance improvements
Nullifying empty import_urls upfront so the number of projects with import_url not NULL decreases to 1/5.
Also, now processing batches in blocks of 1000, with a threaded process - a bit experimental.
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Nullifying empty import_urls upfront so the number of projects with import_url not NULL decreases to 1/5.
Also, now processing batches in blocks of 1000, with a threaded process - a bit experimental.