To allow the removal of the gbw_address and gbw_target_central_id columns (T374937), we need to stop reading data from these columns. Places where we read the value of these columns should be updated to first lookup by target using the globalblocks table and then use the relevant ID to find the global_block_whitelist row.
Acceptance criteria
- All code in the GlobalBlocking extension no longer reads data from the gbw_address and gbw_target_central_id columns