chore(ui): remove unused debug pages from tests

[CommanderStorm]

If we add a frontend, I don't think we need these anymore

[nyurik]

should we wait to remove these until after we add the new UI?

[CommanderStorm]

Both approaches are fine for me.

I don't think the pages were very useful to begin with as they just show the basics. 🤷

[nyurik]

i have actually used the demo page many times to validate various things, and as a prototype for other experiments

[CommanderStorm]

🎉

Now that we don't have a frontend anymore, we might as well remove the debug pages, or should I add a page in the frontend for them?

[nyurik]

eventually i hope to have similarly simple experience with our new frontend - where you can explore the data available. Eventually it will be part of maputnik. For now, i don't think we have any alternative simple way to debug data sources - so i don't think we should remove debug.html just yet

[CommanderStorm]

@nyurik is there something you are still missing in the new frontend?
I think all the capabilities noted here are included.

What is not included is the deckgl or leaflet ones, but I don't think that we need to have a specific file for them.