feat(tree): introduce reorg count metrics in new engine (#11226)

crates/engine/tree/src/tree/mod.rs

@@ -1952,6 +1952,7 @@ where
             let old_first = old.first().map(|first| first.block.num_hash());
             trace!(target: "engine::tree", ?new_first, ?old_first, "Reorg detected, new and old first blocks");
 
+            self.update_reorg_metrics(old.len());
             self.reinsert_reorged_blocks(new.clone());
             self.reinsert_reorged_blocks(old.clone());
         }
@@ -1973,6 +1974,12 @@ where
         ));
     }
 
+    /// This updates metrics based on the given reorg length.
+    fn update_reorg_metrics(&self, old_chain_length: usize) {
+        self.metrics.tree.reorgs.increment(1);
+        self.metrics.tree.latest_reorg_depth.set(old_chain_length as f64);
+    }
+
     /// This reinserts any blocks in the new chain that do not already exist in the tree
     fn reinsert_reorged_blocks(&mut self, new_chain: Vec<ExecutedBlock>) {
         for block in new_chain {