chore: allow metrics from libwaku

[Ivansete-status]

Background

We are currently disabling metrics support when building libwaku to work within Status. We did that to temporarily prevent spamming errors to happen. However, we need a proper solution for that so that the metrics will also be available from within the Status app, f.e.

Details

We need to make sure the metrics objects are created by the same thread that populates them. What is happening now is that the metrics objects are being created by the main thread whereas they are populated by The Waku Thread (see)

Instead, we need The Waku Thread to both create such metrics and populate them.