While Elasticsearch ingest pipelines require a node with the `ingest`
role, we don't need to include `ingest node` in the feature name.
There are no official plans, but the Elasticsearch team has discussed removing
the `ingest` role in the future. This also better aligns the Kibana UI with the
Elasticsearch docs.
The PR also makes some related changes to the Kibana docs.
Relates to https://github.com/elastic/elasticsearch/pull/70253.
40f2784f37