Chore: Remove unused Go code (#28852)

* Chore: Remove more unused Go code

Signed-off-by: Arve Knudsen <arve.knudsen@gmail.com>

pkg/plugins/app_plugin.go

@@ -13,11 +13,6 @@ import (
 	"github.com/grafana/grafana/pkg/util/errutil"
 )
 
-type AppPluginCss struct {
-	Light string `json:"light"`
-	Dark  string `json:"dark"`
-}
-
 type AppPlugin struct {
 	FrontendPluginBase
 	Routes []*AppPluginRoute `json:"routes"`

pkg/plugins/models.go

@@ -11,17 +11,14 @@ import (
 )
 
 var (
-	PluginTypeApp        = "app"
-	PluginTypeDatasource = "datasource"
-	PluginTypePanel      = "panel"
-	PluginTypeDashboard  = "dashboard"
+	PluginTypeApp       = "app"
+	PluginTypeDashboard = "dashboard"
 )
 
 type PluginState string
 
 var (
 	PluginStateAlpha PluginState = "alpha"
-	PluginStateBeta  PluginState = "beta"
 )
 
 type PluginSignature string