Add metric for blob nonce gap errors

[mattsse]

Describe the feature

nonce gaps for blob txs are disallowed:

reth/crates/transaction-pool/src/pool/txpool.rs

Lines 1337 to 1345 in b9b61b3

	let Some(ancestor_tx) = self.txs.get(&ancestor) else {
	// ancestor tx is missing, so we can't insert the new blob
	return Err(InsertErr::BlobTxHasNonceGap { transaction: Arc::new(new_blob_tx) })
	};
	if ancestor_tx.state.has_nonce_gap() {
	// the ancestor transaction already has a nonce gap, so we can't insert the new
	// blob
	return Err(InsertErr::BlobTxHasNonceGap { transaction: Arc::new(new_blob_tx) })
	}

we should add a counter for this in a metric

reth/crates/transaction-pool/src/metrics.rs

Line 100 in b9b61b3

pub struct AllTransactionsMetrics {

TODO

• add metric counter
• integrate into existing grafana dashboard
  

  reth/etc/grafana/dashboards/reth-mempool.json

  Line 1 in b9b61b3

  {

Additional context

No response

[leruaa]

I can take this on.

[Rjected]

@leruaa assigned!