feat(opensearch): add SIEM audit users and fix service naming conflict

[joluc]

Pull Request Details

• Renamed dashboard services to -dashboards-ui suffix to avoid conflicts with operator-created services
  • opensearch-logs-dashboards-ui
  • opensearch-siem-dashboards-ui
• Added siemaudit and siemaudit2 users for SIEM audit logs
• Created siem-audit-write-role with write permissions for siem-audit* indices
• Updated siem-write-role to only access siem-logs* indices (changed from siem*)
• Separated SIEM into two data streams:
  • siem-logs* for regular SIEM logs
  • siem-audit* for audit logs
• Created separate index templates and ISM policies for each stream
• Updated SIEM retention to 7 days (matching logs cluster)
• Added test credentials for audit users in ci/test-values.yaml