Draft: Fix cross joins for members_with_parents method

What does this MR do and why?

Related issues: #422405 (closed), #417455 (closed)

Fix cross joins for members_with_parents method. Contributes to reducing usage of active_without_invites_and_requests scope which cross joins to users

Also, extract members_with_parents method to finder class

Reduce omnipresent class size

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