Bump Chart.js from 2.9.4 to 4.2.1 in dashboard examples (#38071)

* Bump Chart.js from 2.9.4 to 4.2.1 in dashboard examples

* Rollback myChart var modification

* Add some padding between tooltip color and text

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Co-authored-by: XhmikosR <xhmikosr@gmail.com>

site/content/docs/5.3/examples/dashboard-rtl/dashboard.js

@@ -38,15 +38,13 @@
       }]
     },
     options: {
-      scales: {
-        yAxes: [{
-          ticks: {
-            beginAtZero: false
-          }
-        }]
-      },
-      legend: {
-        display: false
+      plugins: {
+        legend: {
+          display: false
+        },
+        tooltip: {
+          boxPadding: 3
+        }
       }
     }
   })