organization.findById performance improvements

[epipav]

Changes proposed ✍️

What

🤖 Generated by Copilot at 269d02b

Fixed bugs in the organizationRepository that affected the accuracy of organization statistics. Improved the query logic and performance by using appropriate columns and joins.
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🤖 Generated by Copilot at 269d02b

The member_data subquery had some bugs
That messed up the counts of activities and mugs
So they changed the columns and joins
To filter out the noise
And now the results are more accurate and snug

Why

How

🤖 Generated by Copilot at 269d02b

• Fix member count and activity count logic in member_data subquery of getOrganizationById function (link, link)

Checklist ✅

• Label appropriately with Feature, Improvement, or Bug.
• Add screehshots to the PR description for relevant FE changes
• New backend functionality has been unit-tested.
• API documentation has been updated (if necessary) (see docs on API documentation).
• Quality standards are met.