Report consumed_buffered_packets_count stat to metrics (backport #19900) (#19915)

* Report consumed_buffered_packets_count stat to metrics (#19900)

(cherry picked from commit 34c1a9ac85)

# Conflicts:
#	core/src/banking_stage.rs

* fix conflicts

Co-authored-by: Justin Starry <justin@solana.com>

core/src/banking_stage.rs

@@ -155,6 +155,12 @@ impl BankingStageStats {
                     self.rebuffered_packets_count.swap(0, Ordering::Relaxed) as i64,
                     i64
                 ),
+                (
+                    "consumed_buffered_packets_count",
+                    self.consumed_buffered_packets_count
+                        .swap(0, Ordering::Relaxed) as i64,
+                    i64
+                ),
                 (
                     "consume_buffered_packets_elapsed",
                     self.consume_buffered_packets_elapsed