DEVPROD-3811 Added support for OpenSearch for Jira.

[amierzwicki]

Pull request description

Adds OpenSearch as a search platform option for Jira, following the same pattern used by Confluence.

What changed

Helm chart:

• OpenSearch added as an optional subchart dependency (opensearch.enabled)
• Auto-generated admin credentials via createSecret, or bring-your-own via existingSecretRef
• Init container to wait for OpenSearch readiness before Jira starts
• OpenSearch connection config injected via ADDITIONAL_JIRA_CONFIG_* env vars

Tests:

• JiraOpenSearchTest — verifies secret generation, env vars, and init container
• AdditionalConfigPropertiesTest — verifies custom jira-config.properties injection
• KinD workflow updated with OpenSearch verification for Jira and Bitbucket

Docs:

• New example guide: JIRA_OPENSEARCH.md (bundled + external OpenSearch)
• Updated JIRA.md container docs and CONFIGURATION.md

Checklist

• I have added unit tests
• I have applied the change to all applicable products
• The E2E test has passed (use e2e label)

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