remove obsolete files

[chohner]

Code PR

• I have read through the contributing notes and understand the structure of the package. In particular, if my PR modifies code of plotly.graph_objects, my modifications concern the codegen files and not generated files.
• I have added tests (if submitting a new feature or correcting a bug) or
  modified existing tests.
• For a new feature, I have added documentation examples in an existing or
  new tutorial notebook (please see the doc checklist as well).
• I have added a CHANGELOG entry if fixing/changing/adding anything substantial.
• For a new feature or a change in behaviour, I have updated the relevant docstrings in the code to describe the feature or behaviour (please see the doc checklist as well).

This simply removes three very old files at root level related to building a conda package that obsolete since at least commit 8586a2a (about 2.5 years ago, release v3.2.0). The content is very outdated and its very unlikely that it is going to be useful for anyone.

[nicolaskruchten]

Thanks for this PR! I'm not sure I understand what these files were for initially... how can we be sure they're obsolete?

[chohner]

I added some additional explanation at the end of the PR description. TLDR: conda packages are built on CI and these local script files are not used and VERY out of date

[nicolaskruchten]

Ok thanks for the diligent follow up many months later :)

[nicolaskruchten]

Thanks again! I redid this PR and merged that one to avoid making you resolve a merge conflict :)