gh-36357: CI: Remove ci-wsl, ci-cygwin-standard

    
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These workflows have been failing for a long time and provide no value.

ci-cygwin-standard was already disabled in sagemath/sage - see
https://github.com/sagemath/sage/actions/workflows/ci-cygwin-
standard.yml

The failures of ci-wsl can be seen here:
https://github.com/sagemath/sage/actions/workflows/ci-wsl.yml

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URL: #36357
Reported by: Matthias Köppe
Reviewer(s): Dima Pasechnik