fix(telemetry): set ms unit on duration heatmap y-axes

The three duration heatmaps (transaction, consensus accept, RPC latency)
had an axisLabel of "Duration (ms)" but no unit code, so y-axis tick
values rendered unscaled. Set unit=ms on both the yAxis options and
panel defaults so buckets display as proper millisecond values.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docker/telemetry/grafana/dashboards/consensus-health.json

@@ -384,7 +384,8 @@
           "sort": "desc"
         },
         "yAxis": {
-          "axisLabel": "Duration (ms)"
+          "axisLabel": "Duration (ms)",
+          "unit": "ms"
         }
       },
       "targets": [
@@ -396,7 +397,12 @@
           "legendFormat": "{{le}}",
           "format": "heatmap"
         }
-      ]
+      ],
+      "fieldConfig": {
+        "defaults": {
+          "unit": "ms"
+        }
+      }
     },
     {
       "title": "Close Time: Raw Proposals (Per Node)",

docker/telemetry/grafana/dashboards/rpc-performance.json

@@ -150,7 +150,8 @@
           "sort": "desc"
         },
         "yAxis": {
-          "axisLabel": "Duration (ms)"
+          "axisLabel": "Duration (ms)",
+          "unit": "ms"
         }
       },
       "targets": [
@@ -162,7 +163,12 @@
           "legendFormat": "{{le}}",
           "format": "heatmap"
         }
-      ]
+      ],
+      "fieldConfig": {
+        "defaults": {
+          "unit": "ms"
+        }
+      }
     },
     {
       "title": "Overall RPC Throughput",

docker/telemetry/grafana/dashboards/transaction-overview.json

@@ -186,7 +186,8 @@
           "sort": "desc"
         },
         "yAxis": {
-          "axisLabel": "Duration (ms)"
+          "axisLabel": "Duration (ms)",
+          "unit": "ms"
         }
       },
       "targets": [
@@ -198,7 +199,12 @@
           "legendFormat": "{{le}}",
           "format": "heatmap"
         }
-      ]
+      ],
+      "fieldConfig": {
+        "defaults": {
+          "unit": "ms"
+        }
+      }
     },
     {
       "title": "Transaction Apply Duration per Ledger",