.github/workflows/ci-cygwin*: Remove build of removed packages #29823
Description
Follow-up from #29754
https://github.com/mkoeppe/sage/runs/746379488
Depends on #29754
CC: @dimpase @kliem @jhpalmieri
Component: porting: Cygwin
Author: Matthias Koeppe
Branch/Commit: 0028328
Reviewer: Jonathan Kliem
Issue created by migration from https://trac.sagemath.org/ticket/29823