Allows to override metabase db cfg values

[ypc-faros]

Description

This change makes it possible to override the db host used to connect to the Faros db from Metabase and whether to use SSL.

After this change is merged, it'll be possible to remove the manual step here from the cloud deployment guide.

We need an extra env var (METABASE_FAROS_DB_HOST) because we still want FAROS_DB_HOST to point to the local host when initializing the cloud deployment, but we need for Metabase to point to the host within the cluster (i.e., the $PLURAL_METABASE_CLUSTERIP in our guide).

After the change is merged, these commands need to be updated (pass METABASE_FAROS_DB_HOST=$PLURAL_METABASE_CLUSTERIP and METABASE_USE_SSL=true) in the guide: 1 2

Type of change

• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

Checklist

• Have you checked to there aren't other open Pull Requests for the same update/change?
• Have you lint your code locally before submission?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you successfully run tests with your changes locally?