Remove `remove_field` option in filter plugins

In https://github.com/elastic/elasticsearch/issues/25441 I proposed to align Elasticsearch Ingest Processors to what has been existing in Logstash so I can imagine the migration to one to the other could be easier.

I think the same conclusion that applied in elasticsearch should apply to logstash as well. So I'm opening this issue for discussion.

My proposal is to remove `remove_field` from all filters but advice people using the mutate filter instead:

```
filter {
mutate {
remove_field => [ "foo" ]
}
}
```

WDYT? Would that make both systems more consistent?