Fix `opensearch.yml` configMap Read-only file system error

[prudhvigodithi]

Description

Coming from an open PR https://github.com/opensearch-project/helm-charts/pull/504, that removes opensearch.yml due to configMap Read-only file system error (as starting 2.12.0 OpenSearch security plugin need RW access to opensearch.yml when passed OPENSEARCH_INITIAL_ADMIN_PASSWORD, for more details ref: https://github.com/opensearch-project/security/issues/3624).

This PR will have a fix to continue use the .Values.config and declare the opensearch.yml and does not throw configMap Read-only file system error.

With this the user can either use the default opensearch.yml or pass the opensearch.yml via .Values.config.

Issues Resolved

https://github.com/opensearch-project/helm-charts/issues/224 part of: https://github.com/opensearch-project/security/issues/3624, https://github.com/opensearch-project/security/issues/3711

Check List

• [x] Commits are signed per the DCO using --signoff

For any changes to files within Helm chart directories:

• [x] Helm chart version bumped
• [x] Helm chart CHANGELOG.md updated to reflect change

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license. For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[prudhvigodithi]

Adding @TheAlgo @smlx @peterzhuamazon , to please have a look.

[prudhvigodithi]

Thanks @derek-ho and @DarshitChanpura.