ILM - add UI option for all allocate settings

[a03nikki]

Describe the feature:

Add the total_shards_per_node allocate action to the Kibana UI for ILM policies.

Related Elasticsearch documentation: https://www.elastic.co/guide/en/elasticsearch/reference/8.8/ilm-allocate.html. The number_of_replicas and the node attributes are options, but not the total_shards_per_node.

If it is not possible to add it, then maybe add an advanced by JSON option that will display and edit complex settings as an JSON entry box if they do not have a UI entry field. This would be more versatile as then each new advanced setting that gets added doesn't need a new entry field added to the UI.

Describe a specific use case for the feature:

Sometimes, it is necessary to set the index.routing.allocation.total_shards_per_node setting on Elasticsearch indices to ensure the active shards that are being written to are spread evenly across the Elasticsearch data_hot nodes, such as new Elasticsearch nodes being added. However, the number of data_cold and data_frozen nodes are significantly fewer. Therefore, limiting the maximum number of shards per node for an index would prevent the shards from allocating. At this point, the shards can clump together again because they are being read instead of written to and a higher data density can be achieved. Thus, the setting needs to be removed.

[elasticmachine]

Pinging @elastic/platform-deployment-management (Team:Deployment Management)

[elasticmachine]

Pinging @elastic/kibana-management (Team:Kibana Management)