Alternatively, we could remove this setting completely and always assume we want to process unique visitors across websites. I'm not sure there is any reason not to want this enabled?
@mattab can you recreate the PR against 4.x-dev and then also fix the UI test (there is a diagnostics config test failing)
@mattab this PR will very likely cause issues because it will only work when
enable_fingerprinting_across_websites is also enabled. This is a privacy issue though. As a result archiving will break with roll up reporting etc. I reckon this PR should be reverted.