Add a simple mode to merge request API
The current "basic" merge request API still loads too much data. For integrations like the Trello Power-up, we just need the basics.
On a canary node for 100 merge requests, it takes < 500 ms to load this data as opposed to 1-1.5 s for the full details. The payload is also smaller.
Closes #34920 (closed)
Edited by Stan Hu