Removed `subscribed` from email recipient filter validity check
Removed `subscribed` from email recipient filter validity check

- `subscribed` will soon cease to be a column on a member and I get errors
  in tests that stem from this block of code because it no longer exists
- AFAICT this block of code is only used to verify the filter is valid
  to filter on, which we should be able to do even if we remove
  `subscribed`
- this commit removes `subscribed` from the filter

TryGhost/Ghost,TryGhost/Ghost,TryGhost/Ghost