fix(editor): Update image sizes in template description not to be full width always (#8037)

## Summary
Update image sizes in template description not to be full width always.


## Related tickets and issues

https://linear.app/n8n/issue/ADO-1506/bug-fix-images-in-template-descriptions


## Review / Merge checklist
- [X] PR title and summary are descriptive. **Remember, the title
automatically goes into the changelog. Use `(no-changelog)` otherwise.**
([conventions](https://github.com/n8n-io/n8n/blob/master/.github/pull_request_title_conventions.md))
- [ ] [Docs updated](https://github.com/n8n-io/n8n-docs) or follow-up
ticket created.
- [x] Tests included.
> A bug is not considered fixed, unless a test is added to prevent it
from happening again.
   > A feature is not complete without tests.

packages/design-system/src/components/N8nMarkdown/Markdown.vue

@@ -247,10 +247,7 @@ export default defineComponent({
 	}
 
 	img {
-		width: 100%;
-		max-height: 90vh;
-		object-fit: cover;
-		border: var(--border-width-base) var(--color-foreground-base) var(--border-style-base);
+		max-width: 100%;
 		border-radius: var(--border-radius-large);
 	}