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

- Stack version: 8.19.18-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-79897 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/45219

Latest 5 failed builds:
- https://buildkite.com/elastic/integrations/builds/45764
- https://buildkite.com/elastic/integrations/builds/45840
- https://buildkite.com/elastic/integrations/builds/45910
- https://buildkite.com/elastic/integrations/builds/45971
- https://buildkite.com/elastic/integrations/builds/46035

Start by reproducing the MongoDB package system test for the collstats data stream and inspect the configuration that produces metrics-mongodb.collstats documents. Compare the reported undefined fields with the expected document fields; done means the collstats test passes in the LogsDB-enabled 8.19.18-SNAPSHOT build.

Written by the indexing model from the issue text.