Markdown flicker

### Current Behavior

When updating a mermaid markdown chart data the full chart rerenders and also briefly displays the raw mermaid code before correctly rendering the chart.


It seems like some child divs are removed and added back for each rerender.
I could not find any recent changes to [UIMarkdown.vue](https://github.com/FlowFuse/node-red-dashboard/blob/main/ui/src/widgets/ui-markdown/UIMarkdown.vue) did anything else in relation to rendering change as this worked in 1.22

### Expected Behavior

Before it rerendered without flickering making smooth animations possible

### Steps To Reproduce

create a mermaid chart and update it with msg data

### Environment

- Dashboard version: 1.24.2
- Node-RED version:
- Node.js version:
- npm version:
- Platform/OS: Raspbian
- Browser: Brave and Chromium

### Have you provided an initial effort estimate for this issue?

I am not a FlowFuse team member