[Stack 8.19.18-SNAPSHOT] [mongodb] Failing test daily: system test: collstats in mongodb.collstats

- Stack version: 8.19.18-SNAPSHOT
- 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-15937 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/45218

Latest 5 failed builds:
- https://buildkite.com/elastic/integrations/builds/45763
- https://buildkite.com/elastic/integrations/builds/45841
- https://buildkite.com/elastic/integrations/builds/45909
- https://buildkite.com/elastic/integrations/builds/45972
- https://buildkite.com/elastic/integrations/builds/46036

Start with the MongoDB system test named "collstats" and the collstats data stream, then compare the failures from build 45218 and the latest listed builds. Trace why mongodb.collstats.stats.capped, freeStorageSize, and scaleFactor are undefined; done means the system test passes without document errors.

Written by the indexing model from the issue text.