Role for auditing-timescaledb.

[Gerrit91]

Description

References:

• Allow additional auditing backend based on TimescaleDB metal-api#565
• Implement audit backend for TimescaleDB. metal-lib#151
• Configuring auditing with timescaledb. mini-lab#217

Actions Required

Another audit backend based on Postgres and TimescaleDB was added as an alternative to the existing Meilisearch backend. 

For this, the variables `metal_auditing_enabled`, `metal_auditing_index_prefix`, `metal_auditing_index_interval`, `metal_auditing_url` were renamed to `metal_auditing_meili_enabled`, `metal_auditing_meili_index_prefix`, `metal_auditing_meili_index_interval`, `metal_auditing_meili_url`. Please adapt your deployment accordingly. 

If you switch the backend, be aware that backup data of the Meilisearch backend remains and manual cleanup is required.