GET _cat/shards?local and GET _cat/indices?local are not completely local

[DaveCTurner]

The cat shards and cat indices APIs perform a ClusterStateAction then a IndicesStatsAction. They accept the ?local parameter and passes this to the ClusterStateAction but this parameter has no effect on the IndicesStatsAction. This is surprising, because GET _cat/shards?local and GET _cat/indices?local look like they might be completely local calls but in fact they still depend on every data node in the cluster.

I think the ?local parameter does not make sense on these APIs and we should remove it.

Relates #50088 which is the same issue for GET _cat/nodes.

[elasticmachine]

Pinging @elastic/es-core-features (:Core/Features/CAT APIs)

[boicehuang]

Do _cat/indices?local have the same behavior?

[DaveCTurner]

Yes, GET _cat/indices?local is also nonlocal as it also uses a cluster-wide indices stats request.

[boicehuang]

May I work on this one? Any hints are appreciated.

[DaveCTurner]

Sure, go ahead. See #50088 for a good example of deprecating and removing a REST parameter like this.

[danhermann]

The local parameters have been deprecated in 7.x and removed for 8.x.