Explore if allowPrerelease fixes vs22 preview rejections

I edited the json wrong in dotnet#51558. If this is all that's needed, the fix can be simpler. I think this likely isn't the case since there are tests with a custom global.json file, but it's worth trying.

Author: nagilson

global.json

@@ -16,10 +16,13 @@
   "native-tools": {
     "cmake": "latest"
   },
+  "sdk": {
+    "allowPrerelease": true
+  },
   "msbuild-sdks": {
     "Microsoft.DotNet.Arcade.Sdk": "9.0.0-beta.25515.2",
     "Microsoft.DotNet.Helix.Sdk": "9.0.0-beta.25515.2",
     "Microsoft.Build.NoTargets": "3.7.0",
     "Microsoft.DotNet.CMake.Sdk": "9.0.0-beta.24217.1"
   }
-}
+}