Investigate better storing of metrics in Mongo

[dillu24]

Rationale

The aim of this ticket is to obtain a database design for storing the metric values in the best way possible. When doing this we must keep the following in mind:

• Metric values are stored in such a way that the UI can query them easily
• The UI needs both historical values of a metric and the current value of a metric
• We should try to assess whether we can do without Redis for storing the current value of a metric

For ticket closure

Come up with a database design that share this on confluence

[dillu24]

Keep #192 in mind when designing a new way of storing contract metrics