Refactor-v-html-markdown.vue

What does this MR do and why?

Replaces dangerous v-html with our safe directive v-safe-html
Closes - #241888 (closed) Remove v-html from app/assets/javascripts/notebook/cells/markdown.vue

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app/assets/javascripts/notebook/cells/markdown.vue

@@ -154,7 +154,7 @@ export default {
       renderer.attachments = this.cell.attachments;
       renderer.relativeRawPath = this.relativeRawPath;
 
-      return marked(this.cell.source.join('').replace(/\\/g, '\\\\')); 
+      return marked(this.cell.source.join('').replace(/\\/g, '\\\\'));
     },
   },
   markdownConfig,