[BUG][Opensearch] Cannot merge custom config opensearch.yml parameters with default ones: Ignoring non-table value

[jetnet]

Describe the bug
I'd like to merge the default Opensearch configuration parameters with my custom ones from the config values. The custom parameters are defined as a map, but getting an error.

To Reproduce
Steps to reproduce the behavior:

1. Create a values file _values-master.yaml:

config:
  opensearch.yml:
    indexing_pressure.memory.limit: "50%"

2. Create templates:

helm template --values _values-master.yaml  --version 2.26.0 -n opensearch-test opensearch-test-master opensearch/opensearch

3. See error

coalesce.go:289: warning: destination for opensearch.config.opensearch.yml is a table. Ignoring non-table value (cluster.name: opensearch-cluster

# Bind to all interfaces because we don't know what IP address Docker will assign to us.
network.host: 0.0.0.0

# Setting network.host to a non-loopback address enables the annoying bootstrap checks. "Single-node" mode disables them again.
# Implicitly done if ".singleNode" is set to "true".
# discovery.type: single-node

# Start OpenSearch Security Demo Configuration
# WARNING: revise all the lines below before you go into production
plugins:
  security:
    ssl:
      transport:
        pemcert_filepath: esnode.pem
        pemkey_filepath: esnode-key.pem
        pemtrustedcas_filepath: root-ca.pem
        enforce_hostname_verification: false
      http:
        enabled: true
        pemcert_filepath: esnode.pem
        pemkey_filepath: esnode-key.pem
        pemtrustedcas_filepath: root-ca.pem
    allow_unsafe_democertificates: true
    allow_default_init_securityindex: true
    authcz:
      admin_dn:
        - CN=kirk,OU=client,O=client,L=test,C=de
    audit.type: internal_opensearch
    enable_snapshot_restore_privilege: true
    check_snapshot_restore_write_privileges: true
    restapi:
      roles_enabled: ["all_access", "security_rest_api_access"]
    system_indices:
      enabled: true
      indices:
        [
          ".opendistro-alerting-config",
          ".opendistro-alerting-alert*",
          ".opendistro-anomaly-results*",
          ".opendistro-anomaly-detector*",
          ".opendistro-anomaly-checkpoints",
          ".opendistro-anomaly-detection-state",
          ".opendistro-reports-*",
          ".opendistro-notifications-*",
          ".opendistro-notebooks",
          ".opendistro-asynchronous-search-response*",
        ]
######## End OpenSearch Security Demo Configuration ########
)

Generated config map:

---
# Source: opensearch/templates/configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: opensearch-cluster-master-config
  labels:
    helm.sh/chart: opensearch-2.26.0
    app.kubernetes.io/name: opensearch
    app.kubernetes.io/instance: opensearch-test-master
    app.kubernetes.io/version: "2.17.1"
    app.kubernetes.io/managed-by: Helm
    app.kubernetes.io/component: opensearch-cluster-master
data:
  opensearch.yml: |
    indexing_pressure.memory.limit: 50%

Expected behavior
The custom parameter from the _values-master.yaml gets merged with the default Chart's opensearch.yml configuration

Chart Name
opensearch/opensearch

Host/Environment (please complete the following information):

• Helm Version: v3.14.0
• (not applicable) Kubernetes Version: client v1.28.2, server: v1.30.7