text panel: fix $apply already in progress error (#10486)

public/app/plugins/panel/text/module.ts

@@ -66,9 +66,6 @@ export class TextPanelCtrl extends PanelCtrl {
   renderMarkdown(content) {
     if (!this.remarkable) {
       this.remarkable = new Remarkable();
-      this.$scope.$apply(() => {
-        this.updateContent(this.remarkable.render(content));
-      });
     }
 
     this.$scope.$applyAsync(() => {