Introduce more MongbDB indexes

## Background
Currently, many queries to MongoDB fo full collection scans. For big collections such as `run` it creates a lot of pressure for the MongoDB cluster.

## Feature
Investigate production logs and find bottlenecks. Check if corresponding queries can be optimized or new indexes can be added to ease the pressure on MongoDB.

Start by investigating production logs for MongoDB full collection scans and query bottlenecks, focusing especially on the run collection. Review whether each bottleneck can be addressed through query optimization or additional indexes; done means the relevant changes have been identified and added to reduce pressure on the MongoDB cluster.

Vom Indexierungsmodell aus dem Issue-Text verfasst.