Image Rendering: Fix render of graph panel legend aligned to the right using Grafana image renderer plugin/service (#21854)

Don't render class body--phantomjs on body element when 
PhantomJS renderer not is in use.

Fixes #21830

pkg/services/rendering/rendering.go

@@ -20,6 +20,8 @@ func init() {
 	registry.RegisterService(&RenderingService{})
 }
 
+var IsPhantomJSEnabled = false
+
 type RenderingService struct {
 	log             log.Logger
 	pluginInfo      *plugins.RendererPlugin
@@ -69,6 +71,7 @@ func (rs *RenderingService) Run(ctx context.Context) error {
 			"You should consider migrating from phantomJS to grafana-image-renderer plugin. " +
 			"Read more at https://grafana.com/docs/grafana/latest/administration/image_rendering/")
 		rs.renderAction = rs.renderViaPhantomJS
+		IsPhantomJSEnabled = true
 		<-ctx.Done()
 		return nil
 	}