Cleanup plugin examples - remove the ones we don't want to showcase

[Ukochka]

Which plugin examples do we want to cleanup?

Plugin Examples to remove

Beta Give feedback

1. Figure out which plugins to cleanup
2. https://github.com/grafana/grafana-plugin-examples/tree/main/examples/panel-flot
3. https://github.com/grafana/grafana-plugin-examples/tree/main/examples/panel-plotly
4. https://github.com/grafana/grafana-plugin-examples/tree/main/examples/panel-scatterplot
5. https://github.com/grafana/grafana-plugin-examples/tree/main/examples/panel-visx