Recommend conda forge recipe rather than plotly recipe

[marthacryan]

Plotly posts each new release as a recipe on its own anaconda org but the conda forge recipe is more popular by far. There doesn't appear to be a benefit to using our own recipe, and it slows down our CI a lot to build the recipe. It's not working well with the pyproject.toml changes that I've been working on, so we're just going to remove it in that PR #4970.