Rename cluster to storage_cluster_id for apiserver_storage_size_bytes metric

Signed-off-by: Davanum Srinivas <davanum@gmail.com>

test/instrumentation/documentation/documentation-list.yaml

@@ -3209,7 +3209,7 @@
   type: Custom
   stabilityLevel: ALPHA
   labels:
-  - cluster
+  - storage_cluster_id
 - name: terminated_watchers_total
   namespace: apiserver
   help: Counter of watchers closed due to unresponsiveness broken by resource type.

test/instrumentation/documentation/documentation.md

@@ -8,7 +8,7 @@ description: >-
 
 ## Metrics (v1.30)
 
-<!-- (auto-generated 2024 Jan 14) -->
+<!-- (auto-generated 2024 Apr 11) -->
 <!-- (auto-generated v1.30) -->
 This page details the metrics that different Kubernetes components export. You can query the metrics endpoint for these 
 components using an HTTP scrape, and fetch the current metrics data in Prometheus format.
@@ -1094,7 +1094,7 @@ Alpha metrics do not have any API guarantees. These metrics must be used at your
 	<ul>
 	<li><label class="metric_detail">Stability Level:</label><span class="metric_stability_level">ALPHA</span></li>
 	<li data-type="custom"><label class="metric_detail">Type:</label> <span class="metric_type">Custom</span></li>
-	<li class="metric_labels_varying"><label class="metric_detail">Labels:</label><span class="metric_label">cluster</span></li></ul>
+	<li class="metric_labels_varying"><label class="metric_detail">Labels:</label><span class="metric_label">storage_cluster_id</span></li></ul>
 	</div><div class="metric" data-stability="alpha">
 	<div class="metric_name">apiserver_storage_transformation_duration_seconds</div>
 	<div class="metric_help">Latencies in seconds of value transformation operations.</div>