remove spring-cloud extension as it has been deprecated for years (#8897)

Author: evelyn-ys

src/index.json

@@ -559,11 +559,6 @@
     "AzureServiceName": "Azure Sphere",
     "URL": "https://learn.microsoft.com/azure-sphere/"
   },
-  {
-    "Command": "az spring-cloud",
-    "AzureServiceName": "Spring Apps",
-    "URL": "https://learn.microsoft.com/azure/spring-apps"
-  },
   {
     "Command": "az spring",
     "AzureServiceName": "Spring Apps",