fix: diff after converting to html to text (#25582)

(cherry picked from commit a9ebf58)

frappe/public/js/frappe/form/footer/version_timeline_content_builder.js

@@ -283,6 +283,7 @@ function format_content_for_timeline(content) {
 	// limits content to 40 characters
 	// escapes HTML
 	// and makes it bold
+	content = frappe.utils.html2text(content);
 	content = frappe.ellipsis(content, 40) || '""';
 	content = frappe.utils.escape_html(content);
 	return content.bold();