[#219] Resolve "Etcd: move security logs to opensearch"

Closes #219

• created audit-opensearch.js that can replace audit.js
  • only auditIP is currently used, to audit-security-<instance>-YYYY.MM
• Created index: https://es-notifications-audit1.cern.ch/dashboards/app/management/opensearch-dashboards/indexPatterns
• Index names audit-<name>-<instance>-YYYY.MM to facilitate cleanup by month.
• Cluster documentation: https://notifications-internal.docs.cern.ch/operations/es-auditing/

Requires new env variables:

OPENSEARCH_AUDITING=true
OPENSEARCH_HOST=https://es-notifications-audit1.cern.ch/es
# OPENSEARCH_PORT=443
OPENSEARCH_USER=audituser
OPENSEARCH_PASSWORD=fill-me
# dev / qa / prod
OPENSEARCH_SUFFIX=prod