[sceneVariablesSetToVariables]: Use type guards from scenes to type variable (#78488)

* Update grafana/scenes version to 1.24.0

* Use type guards to properly type variables

* Update scenes to version 1.24.1

package.json

@@ -254,7 +254,7 @@
     "@grafana/lezer-traceql": "0.0.10",
     "@grafana/monaco-logql": "^0.0.7",
     "@grafana/runtime": "workspace:*",
-    "@grafana/scenes": "^1.23.1",
+    "@grafana/scenes": "1.24.1",
     "@grafana/schema": "workspace:*",
     "@grafana/ui": "workspace:*",
     "@kusto/monaco-kusto": "^7.4.0",