layere: record residency changes with download/evict

pageserver/src/tenant/storage_layer.rs

@@ -984,6 +984,11 @@ impl LayerE {
                 kind: tokio::sync::OnceCell::default(),
             });
 
+            self.access_stats.record_residence_event(
+                LayerResidenceStatus::Resident,
+                LayerResidenceEventReason::ResidenceChange,
+            );
+
             Ok(if self.wanted_evicted.load(Ordering::Acquire) {
                 // because we reset wanted_evictness earlier, this most likely means when we were downloading someone
                 // wanted to evict this layer.
@@ -1156,6 +1161,8 @@ impl LayerE {
 
                     let res = capture_mtime_and_delete.await;
 
+                    this.access_stats.record_residence_event(LayerResidenceStatus::Evicted, LayerResidenceEventReason::ResidenceChange);
+
                     drop(this.status.send(Status::Evicted));
 
                     match res {