fix(metrics): update latest ingested block on reorg (#515)

Chainhook's `chainhook_stx_highest_block_ingested` and
`chainhook_btc_highest_block_ingested` metrics were not being updated on
a reorg. This was causing the Chainhook node to appear to be lagging
behing the source chains, event though Chainhook's reorg handler was
functioning properly.

This PR sets the highest block ingested metrics on a reorg based on the
highest index block being applied in the reorg.

components/chainhook-sdk/src/observer/mod.rs

@@ -971,11 +971,16 @@ pub async fn start_observer_commands_handler(
                             .iter()
                             .max_by_key(|b| b.block_identifier.index)
                         {
-                            Some(highest_tip_block) => prometheus_monitoring.btc_metrics_set_reorg(
-                                highest_tip_block.timestamp.into(),
-                                blocks_to_apply.len() as u64,
-                                blocks_to_rollback.len() as u64,
-                            ),
+                            Some(highest_tip_block) => {
+                                prometheus_monitoring.btc_metrics_set_reorg(
+                                    highest_tip_block.timestamp.into(),
+                                    blocks_to_apply.len() as u64,
+                                    blocks_to_rollback.len() as u64,
+                                );
+                                prometheus_monitoring.btc_metrics_ingest_block(
+                                    highest_tip_block.block_identifier.index,
+                                );
+                            }
                             None => {}
                         }
 
@@ -1183,12 +1188,16 @@ pub async fn start_observer_commands_handler(
                             .iter()
                             .max_by_key(|b| b.block.block_identifier.index)
                         {
-                            Some(highest_tip_update) => prometheus_monitoring
-                                .stx_metrics_set_reorg(
+                            Some(highest_tip_update) => {
+                                prometheus_monitoring.stx_metrics_set_reorg(
                                     highest_tip_update.block.timestamp,
                                     update.blocks_to_apply.len() as u64,
                                     update.blocks_to_rollback.len() as u64,
-                                ),
+                                );
+                                prometheus_monitoring.stx_metrics_ingest_block(
+                                    highest_tip_update.block.block_identifier.index,
+                                )
+                            }
                             None => {}
                         }
                     }