Schema: Implement v2beta1 → v2alpha1 conversion (#113876)

apps/dashboard/pkg/migration/testdata/input/v15.no-op-migration.json

@@ -32,7 +32,9 @@
         {
           "name": "server",
           "type": "query",
-          "datasource": "prometheus",
+          "datasource": {
+            "type": "prometheus"
+          },
           "query": "label_values(server)",
           "refresh": 1,
           "options": []

apps/dashboard/pkg/migration/testdata/output/latest_version/v15.no-op-migration.v42.json

@@ -89,7 +89,9 @@
   "templating": {
     "list": [
       {
-        "datasource": "prometheus",
+        "datasource": {
+          "type": "prometheus"
+        },
         "name": "server",
         "options": [],
         "query": "label_values(server)",

apps/dashboard/pkg/migration/testdata/output/single_version/v15.no-op-migration.v15.json

@@ -58,7 +58,9 @@
   "templating": {
     "list": [
       {
-        "datasource": "prometheus",
+        "datasource": {
+          "type": "prometheus"
+        },
         "name": "server",
         "options": [],
         "query": "label_values(server)",