cmd, ethdb, vendor: integrate leveldb iostats (#16277)

* cmd, dashboard, ethdb, vendor: send iostats to dashboard

* ethdb: change names

* ethdb: handle parsing errors

* ethdb: handle iostats syntax error

* ethdb: r -> w

vendor/github.com/syndtr/goleveldb/leveldb/memdb/memdb.go

@@ -329,7 +329,7 @@ func (p *DB) Delete(key []byte) error {
 
 	h := p.nodeData[node+nHeight]
 	for i, n := range p.prevNode[:h] {
-		m := n + 4 + i
+		m := n + nNext + i
 		p.nodeData[m] = p.nodeData[p.nodeData[m]+nNext+i]
 	}