Add appropriate prefixes to the Edge metrics

[Stefan-Ethernal]

Description

This PR accommodates prefixes to the existing Edge metrics in order to categorize and align them with the documentation: https://wiki.polygon.technology/docs/edge/configuration/prometheus-metrics/.

Existing metrics fall into 3 categories: consensus, network and tx pool.

Changes include

• Bugfix (non-breaking change that solves an issue)
• Hotfix (change that solves an urgent issue, and requires immediate attention)
• New feature (non-breaking change that adds functionality)
• Breaking change (change that is not backwards-compatible and/or changes current functionality)

Breaking changes

Datadog dashboards need to be changed in order to include renamed metrics.

Checklist

• I have assigned this PR to myself
• I have added at least 1 reviewer
• I have added the relevant labels
• I have updated the official documentation
• I have added sufficient documentation in code

Testing

• I have tested this code with the official test suite
• I have tested this code manually

[codecov]

Codecov Report

Merging #1043 (b6ee1bb) into develop (9cde1e3) will increase coverage by 0.00%.
The diff coverage is 75.00%.

@@           Coverage Diff            @@
##           develop    #1043   +/-   ##
========================================
  Coverage    53.88%   53.89%           
========================================
  Files          132      132           
  Lines        17564    17566    +2     
========================================
+ Hits          9465     9467    +2     
  Misses        7451     7451           
  Partials       648      648           

Impacted Files	Coverage Δ
consensus/ibft/ibft.go	1.62% <0.00%> (ø)
network/server.go	75.00% <100.00%> (+0.10%)	⬆️
network/server_identity.go	94.11% <100.00%> (ø)
txpool/txpool.go	73.48% <100.00%> (ø)

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[vcastellm]

LGTM

[ZeljkoBenovic]

LGTM 🚀

After we merge this PR, we'll need to update our docs as well as our own Prometheus scrapers.
What's changed:

• txpool_pending_transactions => edge_txpool_pending_transactions
• consensus_validators => edge_consensus_validators
• consensus_rounds => does not exist anymore -- we should restore this metric asap
• consensus_num_txs => edge_consensus_num_txs
• consensus_block_interval => edge_consensus_block_interval
• network_peers => edge_network_peers
• network_outbound_connections_count => edge_network_outbound_connections_count
• network_inbound_connections_count => edge_network_inbound_connections_count
• network_pending_outbound_connections_count => edge_network_pending_outbound_connections_count
• network_pending_inbound_connections_count => edge_network_pending_inbound_connections_count

[Stefan-Ethernal]

consensus_rounds => does not exist anymore -- we should restore this metric asap

Not sure where it has vanished, but good point. 🙂 Let me try find it in git history and re-introduce it.

EDIT:
I did some research and it turns out that consensus_rounds has been removed with introduction of IBFT 2.0 (#650, https://github.com/0xPolygon/polygon-edge/pull/650/files#diff-496bebdd7de5ae02eb3ea22e95ac9270069798437f3477475ee59fb60dca0492L503). Due to the fact that consensus engine has changed quite a lot, not sure how we can re-establish this metric back.

We can consider maybe doing something similar like we did for the polybft (although in the polybft it denotes how many rounds did it take to seal a block and is available only after block is finalized and inserted): https://github.com/0xPolygon/polygon-edge/pull/650/files#diff-496bebdd7de5ae02eb3ea22e95ac9270069798437f3477475ee59fb60dca0492L503.

[ZeljkoBenovic]

With the introduction of go-ibft, consensus_rounds metric is "buried" in the go-ibft module itself and needs to be exposed in that package.

Restoring this metric should probably be a dedicated task...

[ZeljkoBenovic]

Just to clarify.
We already had these prefixes in place, as we can clearly see in our public docs, but it looks like they vanished when edge prefix was added.
This is how these metrics look like currently (before this PR):

edge_block_interval
edge_inbound_connections_count
edge_num_txs
edge_outbound_connections_count
edge_peers
edge_pending_inbound_connections_count
edge_pending_outbound_connections_count
edge_pending_transactions
edge_validators