Suggestions: Deprecate the old API and put external suggestions behind a flag (#114127)

* Suggestions: Deprecate previous API, enable external plugin suggestions behind flag

* fix types for deprecated builder

* restore some support for cloud-onboarding

* add support for cloud-onboarding usage, add test to ensure it keeps working

* refactor to not hardcode on 'core:'

* remove unused import

pkg/services/featuremgmt/registry.go

@@ -1884,6 +1884,14 @@ var (
 			Owner:        grafanaDatavizSquad,
 			Expression:   "false",
 		},
+		{
+			Name:         "externalVizSuggestions",
+			Description:  "Enable all plugins to supply visualization suggestions (including 3rd party plugins)",
+			Stage:        FeatureStageExperimental,
+			FrontendOnly: true,
+			Owner:        grafanaDatavizSquad,
+			Expression:   "false",
+		},
 		{
 			Name:         "preventPanelChromeOverflow",
 			Description:  "Restrict PanelChrome contents with overflow: hidden;",

pkg/services/featuremgmt/toggles_gen.csv

@@ -256,6 +256,7 @@ cdnPluginsUrls,experimental,@grafana/plugins-platform-backend,false,false,false
 pluginInstallAPISync,experimental,@grafana/plugins-platform-backend,false,false,false
 newGauge,experimental,@grafana/dataviz-squad,false,false,true
 newVizSuggestions,preview,@grafana/dataviz-squad,false,false,true
+externalVizSuggestions,experimental,@grafana/dataviz-squad,false,false,true
 preventPanelChromeOverflow,preview,@grafana/grafana-frontend-platform,false,false,true
 jaegerEnableGrpcEndpoint,experimental,@grafana/oss-big-tent,false,false,false
 pluginStoreServiceLoading,experimental,@grafana/plugins-platform-backend,false,false,false

pkg/services/featuremgmt/toggles_gen.json

@@ -1383,6 +1383,20 @@
         "codeowner": "@grafana/identity-access-team"
       }
     },
+    {
+      "metadata": {
+        "name": "externalVizSuggestions",
+        "resourceVersion": "1763498528748",
+        "creationTimestamp": "2025-11-18T20:42:08Z"
+      },
+      "spec": {
+        "description": "Enable all plugins to supply visualization suggestions (including 3rd party plugins)",
+        "stage": "experimental",
+        "codeowner": "@grafana/dataviz-squad",
+        "frontend": true,
+        "expression": "false"
+      }
+    },
     {
       "metadata": {
         "name": "extraThemes",