[3.12] gh-128446: Skip Windows CI for Unix build system changes (GH-128450) (#130435)

(cherry picked from commit b05fa90b21dd01bb836285cdd41920320b09e681)

Authored-by: Adam Turner <9087854+aa-turner@users.noreply.github.com>
Co-authored-by: Srinivas Reddy Thatiparthy (తాటిపర్తి శ్రీనివాస్  రెడ్డి) <thatiparthysreenivas@gmail.com>
Co-authored-by: Adam Turner <9087854+aa-turner@users.noreply.github.com>