[BUG] Index creation fails when index.replication.type is not mentioned while cluster setting cluster.remote_store.enabled is true

[ashking94]

Describe the bug
As the title says, the index creation in a remote store enabled cluster fails when the index.replication.type is not mentioned. The index.replication.type index setting is implied to be SEGMENT when cluster.remote_store.enabled is set to true in opensearch.yml before the bootstrap.

Response when we try to create an index without specifying index.replication.type on a remote enabled cluster -

➜  opensearch curl -X PUT "localhost:9200/test-index?pretty" -H 'Content-Type: application/json' -d'
{
  "settings": {
    "number_of_shards": 1,
    "number_of_replicas": 1,
    "index.remote_store.translog.buffer_interval" : "300ms"
  }
}
'
{
  "error" : {
    "root_cause" : [
      {
        "type" : "illegal_argument_exception",
        "reason" : "To enable index.remote_store.enabled, index.replication.type should be set to SEGMENT"
      }
    ],
    "type" : "illegal_argument_exception",
    "reason" : "To enable index.remote_store.enabled, index.replication.type should be set to SEGMENT"
  },
  "status" : 400
}

To Reproduce
Steps 1 - Update the opensearch.yml with below settings -

1. cluster.remote_store.enabled=true
2. cluster.remote_store.segment.repository=<valid_repo>
3. cluster.remote_store.translog.repository=<valid_repo>

Step 2 - Register the <valid_repo> as mentioned in above step.

Step 3 - Create index as mentioned in Describe the bug section.

Expected behavior
The index creation should pick the SEGMENT replication implicitly and not fail index creation.

Plugins
Please list all plugins currently enabled.

Screenshots
If applicable, add screenshots to help explain your problem.

Host/Environment (please complete the following information):

• OS: [e.g. iOS]
• Version [e.g. 22]

Additional context
Add any other context about the problem here.