[Issue][Logstash] Clarify what we mean between "ignored" and "may cause errors"

### Type of issue

None

### What documentation page is affected

https://www.elastic.co/docs/reference/logstash/plugins/plugins-outputs-elasticsearch

### What happened?

There are multiple places on this page with caveats for Serverless that say, for example:

> The Index lifecycle management (ILM) feature does not apply for Elasticsearch Serverless. Any ILM settings in your plugin configuration are ignored and may cause errors.

I'm assuming ILM settings are ignored and because they are ignored they won't cause problems. Or are we saying they are ignored but will still cause problems so the user had better remove them?

### Additional info

_No response_