MembersFinder gives unexpected results with :invited_groups

In !48372 (merged), I exposed the include_relations option of MembersFinder to the GraphQL API.

While writing the tests for this, I noticed that if you pass include_relations: [:invited_groups], you actually get direct and inherited members for the project too: !48372 (comment 453452121)

This is probably a bit of an edge case in the API right now, but I would consider it a bug: if we have this level of granularity, I'd expect to only get members from invited groups if that's what I asked for.