docs: align core metrics documentation with implementation

[kurahin]

The core metrics table was out of sync with the actual metrics exposed by the node.
This change removes obsolete entries, adds missing metrics from the consensus, p2p, mempool, state and blocksync packages, and fixes incorrect types (e.g. consensus_chain_size_bytes is a counter, not a gauge). This keeps the Prometheus
metrics documentation accurate and matchable to the current code.

---

Note

Keeps Prometheus metrics documentation accurate with the current node implementation.

• Rewrites docs/explanation/core/metrics.md metrics table to reflect actual metrics
• Adds missing consensus/p2p entries (e.g., consensus_quorum_precommit_delay, consensus_precommits_*, consensus_peer_height, per-peer/channel P2P byte counters, reactor processing metrics)
• Removes outdated/unused metrics and fields; fixes tag names (validator_address, peer_id, etc.) and metric types (e.g., consensus_chain_size_bytes is a Counter)
• Minor formatting/consistency cleanup in names and tags

^{Written by Cursor Bugbot for commit 52f24f0. This will update automatically on new commits. Configure here.}