Remove unnecessary groupbys in session queries

[EDsCODE]

Changes

Please describe.

• the innermost section in session queries have a groupby that doesn't seem to be achieving anything
• this optimizes the runtime of the sessions queries

If this affects the frontend, include screenshots.

Checklist

• All querysets/queries filter by Organization, by Team, and by User
• Django backend tests
• Jest frontend tests
• Cypress end-to-end tests

[mariusandra]

I guess the group bys are there to prevent duplicate events (same uuid) from being counted twice?

I think it's fine to remove, yet I've been away from these queries for a while now and I'm hesitant to be 100% confident in my approval.

[EDsCODE]

Yeah I think in theory it shouldve been deduping if necessary, but I ran some counts to compare if it actually has any effect and doesn't seem to be changing anything with the results.

[timgl]

These may have been necessary: #3566 (comment)

[mariusandra]

Yep, they probably were. The tests started flaking after that, though surprisingly sometimes pass fully. This is what I consistently get when running the tests locally:

[timgl]

Yep, I'll fix this right now

[mariusandra]

Yep, this should be reverted. After adding back the groupbys, all tests went green

[timgl]

I'm not going to revert it but one sec!

[timgl]

#3580