Remove all dev/ci requirements.txt and fully replace with pixi

[Wumpf]

What

• Fixes Replace non-example requirements.txt files with pixi #5895

In the process cleans up quite a bit more ci to use the pixi environment consequently.

Note that the process I followed here was essentially:

• pick a requirements.txt file
• check for each of its package if it's already in pixi
  • if not, try adding it as conda package to pixi
    • if not add it as pypi package to pixi
    • try documenting who uses it
• repeat until requirements.txt file is empty
• remove mentions of the requirements.txt file, ensure that python invocations below are using pixi

Checklist

• I have read and agree to Contributor Guide and the Code of Conduct
• I've included a screenshot or gif (if applicable)
• I have tested the web demo (if applicable):
  • Using examples from latest main build: rerun.io/viewer
  • Using full set of examples from nightly build: rerun.io/viewer
• The PR title and labels are set such as to maximize their usefulness for the next release's CHANGELOG
• If applicable, add a new check to the release checklist!

• PR Build Summary
• Recent benchmark results
• Wasm size tracking

[github-actions]

Deployed docs

Commit	Link
806c68a	https://landing-bezia709z-rerun.vercel.app/docs

[emilk]

Looks good if tested, and if you have searched for the removed scripts so that they are not referred to from anywhere

[Wumpf]

if you have searched for the removed scripts

I did, but given my track record I better do another round 😅