[Infra] Fix broken test

Fix test broken by change in behaviour in .NET 10.

Author: martincostello

test/OpenTelemetry.Instrumentation.AspNetCore.Tests/RouteTests/README.net10.0.md

@@ -455,7 +455,7 @@
   "IdealHttpRoute": "/Index",
   "ActivityDisplayName": "GET",
   "ActivityHttpRoute": "",
-  "MetricHttpRoute": "",
+  "MetricHttpRoute": "/",
   "RouteInfo": {
     "HttpMethod": "GET",
     "Path": "/",

test/OpenTelemetry.Instrumentation.AspNetCore.Tests/RouteTests/RoutingTestCases.json

@@ -135,6 +135,17 @@
     "currentHttpRoute": "",
     "expectedHttpRoute": "/Index"
   },
+  {
+    "name": "Root path",
+    "testApplicationScenario": "RazorPages",
+    "minimumDotnetVersion": 10,
+    "httpMethod": "GET",
+    "path": "/",
+    "expectedStatusCode": 200,
+    "currentHttpRoute": "",
+    "expectedHttpRoute": "/Index",
+    "expectedMetricRoute": "/"
+  },
   {
     "name": "Index page",
     "testApplicationScenario": "RazorPages",