fix(server): dataloader batching being broken

[fabis94]

ever since multi region dataloaders, they were not properly batching up SQL queries

for that big connectors query this reduced SQL counts from 121 to 42 locally, and that is with multiple regions, where each region has to have its own cache and query. so the number will be even lower for people with all data in the same region

edit: also introduced Stream/Project.collaborators dataloader, which cut that 42 SQL op count in half down to just 18