Binder builds on PRs are consistently timing out

[krassowski]

The binder builds on PRs are timing out all the time. In last couple of weeks I did not have a single build succeed. Here are some ideas:

• publish the assets built on CI for each PR as "releases" to GitHub package registry https://docs.github.com/en/packages/learn-github-packages/introduction-to-github-packages and pull them on Binder, install from a wheel and have the binder up in 1 minute or so (after CI has done its thing of course)
• remove the extra build steps (prod:minimize:report) and hope we will be able to test something rather than nothing
• use a docker image from Use docker on CI to speed it up #15916 ?

jupyterlab/binder/postBuild

Line 17 in 9231bc3

(time yarn build:dev:prod:minimize:report) 2>&1 | tee _reports_/01_build.txt

CC @bollwyvl who was maintaining the Binder scripts last few times and may have opinions