Bugfix: Target notifications groups/users added to channel members
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Check Drupal usecase: https://notifications.web.cern.ch/channels/463142b8-ea4b-428a-ab9c-fbc37305f040/notifications
Seems like all direct notifications' targets are being added to the channels members, without checking if they are already member via other group or users.
Double check if this implementation was intentional, could be a performance decision.
Link items together to show that they're related or that one is blocking others.