[LogsDB] [Stack 8.19.22-SNAPSHOT] [mongodb] Failing test daily: system test: collstats in mongodb.collstats

- Stack version: 8.19.22-SNAPSHOT
- LogsDB: enabled
- Package: mongodb
- Failing test: system test: collstats
- DataStream: collstats
- Owners:
- @elastic/obs-infraobs-integrations

Failure:
```
test case failed: one or more errors found in documents stored in metrics-mongodb.collstats-12163 data stream: [0] field "mongodb.collstats.stats.capped" is undefined
[1] field "mongodb.collstats.stats.freeStorageSize" is undefined
[2] field "mongodb.collstats.stats.scaleFactor" is undefined
```

First build failed: https://buildkite.com/elastic/integrations/builds/49550

Start with the mongodb package's system test for collstats and the collstats data stream, then inspect how the reported metrics documents are produced. Reproduce the failure against the 8.19.22-SNAPSHOT build and verify that mongodb.collstats.stats.capped, freeStorageSize, and scaleFactor are defined in the stored documents.

Written by the indexing model from the issue text.