Settings: rename "Allow referral marketing" into "Disallow referral marketing"

Description

All ClearURLs settings enforce tracking elements filtering rules when enabled (green), apart from "Allow referral marketing" which does the opposite. This is confusing for new users, so I would rename it into "Disallow referral marketing" or "Block referral marketing" or similar. This way maximum protection would be achieved when all settings are enabled and green.

Affected UI areas

ClearURLs settings page.

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information