Compatibility with OpenSearch 3.1.0

[Jorgesnchz]

Description

We need to ensure the compatibility with the next version of OpenSearch v3.1.0
This update is still being discussed, but we need to be aware of potential issues.

For that, we need to:

• Review opensearch's release notes.
• Identify improvements and potential impact.
• Identify changes on upstream files (listed on Improve versioning of upstream's configuration files #94)
• Create new development branch.
• Develop a testing environment to verify our components would work under this new build.
• Indexer-Dashboard compatibility testing Indexer-Dashboard testing under OpenSearch 3.1.0 #1007.

Issues

• List here the detected issues

[Jorgesnchz]

Release notes highlights

Release notes: https://github.com/opensearch-project/OpenSearch/releases/tag/3.1.0

Dependencies and CVEs:

• Update Apache HttpClient5 and HttpCore5 (CVE-2025-27820) (Update Apache HttpClient5 and HttpCore5 (CVE-2025-27820) opensearch-project/OpenSearch#18152)
• Versions of: Apache Lucene, com.google.code.gson:gson, com.microsoft.azure:msal4j...

Removed settings:

• [repository-s3] Removed existing ineffective server_side_encryption setting (Add support for SSE-KMS and bucket owner verification opensearch-project/OpenSearch#18312)
  Occurrences: https://github.com/search?q=org%3Awazuh%20server_side_encryption&type=code

Interesting features:

• Implement parallel shard refresh behind cluster settings (Implement parallel shard refresh behind cluster settings opensearch-project/OpenSearch#17782)
• Enabled Async Shard Batch Fetch by default (Enabled Async Shard Batch Fetch by default opensearch-project/OpenSearch#18139)
• Enable testing for ExtensiblePlugins using classpath plugins (Enable testing for ExtensiblePlugins using classpath plugins opensearch-project/OpenSearch#16908)