Better show_value margin approach

**Describe the solution you'd like**
Instead of adding padding, disable right axis clipping

<img width="434" alt="image" src="https://user-images.githubusercontent.com/777196/211079162-9a5a5182-4e38-4ca6-b661-e41b2961a8d9.png">




Originally suggested by @quantum-byte [here](https://github.com/dbuezas/lovelace-plotly-graph-card/discussions/43#discussioncomment-4081698)