feat: Update the node's prometheus metrics

[saibatizoku]

Updates jormungandr node to initialize mempool and peer gauges to 0.

Closes input-output-hk/catalyst-core#600

[cong-or]

golden commit: 47e874c

we should make a branch off this and put all changes in here for A/B testing.

[kukkok3]

Would not be better to wait until we have a stable jor node version and merge this change into that?

[cong-or]

Would not be better to wait until we have a stable jor node version and merge this change into that?

yea but we want to compare the "new" nodes performance vs the old node.

[Old:](golden commit: 47e874c)

New: Branch from gold. Silver?

[saibatizoku]

Would not be better to wait until we have a stable jor node version and merge this change into that?

yea but we want to compare the "new" nodes performance vs the old node.

[Old:](golden commit: 47e874c)

New: Branch from gold. Silver?

I think that we can rename to whichever name is better suited to do A/B testing (e.g. branch-A, branch-B), and create a tag when we have reached a conclusion.