Update settings with deepmerge

[Pranoti27]

Update updateSettings method to use existing deepmerge for function to correctly merge settings before updating.

Tested locally -

etcdctl put "/esdock-opensearch-os-cn-tier2-production-cluster-dca/indices/os-cn-mp13n-v1-1001/settings" '{"index":{"pause_pull_ingestion":false,"ingestion_source":{"type":"kafka","pointer.init.reset":"reset_by_timestamp","param":{"topic":"mp13n-os-cloudnative","bootstrap_servers":"kafka-i.phx.uber.internal:9092"},"pointer.init.reset.value":20909090},"refresh_interval":"30s","number_of_shards":1,"replication.type":"SEGMENT","max_result_window":10000,"remote_store.enabled":true,"knn":true,"remote_store.segment.repository":"gcs-snapshot-repository","number_of_replicas":1}}'

Call update settings api -
curl -X PUT "http://localhost:8080/esdock-opensearch-os-cn-tier2-production-cluster-dca/os-cn-mp13n-v1-1001/_settings" \
  -H "Content-Type: application/json" \
  -d '{
    "pause_pull_ingestion": true
  }'

/esdock-opensearch-os-cn-tier2-production-cluster-dca/indices/os-cn-mp13n-v1-1001/settings
{"index":{"number_of_shards":1,"shard_replica_count":[],"num_groups_per_shard":[],"num_ingest_groups_per_shard":[],"pause_pull_ingestion":true,"refresh_interval":"30s","number_of_replicas":1,"ingestion_source":{"type":"kafka","pointer.init.reset":"reset_by_timestamp","param":{"topic":"mp13n-os-cloudnative","bootstrap_servers":"kafka-i.phx.uber.internal:9092"},"pointer.init.reset.value":20909090},"replication.type":"SEGMENT","max_result_window":10000,"remote_store.enabled":true,"knn":true,"remote_store.segment.repository":"gcs-snapshot-repository"}}
`

[GeorgeZhai]

LGTM. left a question

[GeorgeZhai]

question , is this deepMerge following the same logic as Opensearch setting update logic? or if's just a standard object deep merge.
if we want to remove an attribute, do we just pass a null value to remove it?

[Pranoti27]

deepMerge is standard object deep merge. - https://github.com/TejasNaikk/cluster-controller/blob/main/src/main/java/io/clustercontroller/indices/IndexManager.java#L829