[ci/gitlab/windows] Do not load user overlays.
[ci/gitlab/windows] Do not load user overlays.

This was broken since #13177.  We remove support for user overlays in
Windows build instead of fixing it since there is no specific use
case.

ejgallego/coq,JasonGross/coq,Zimmi48/coq,SkySkimmer/coq,JasonGross/coq,JasonGross/coq,SkySkimmer/coq,ejgallego/coq,ejgallego/coq,JasonGross/coq,gares/coq,gares/coq,gares/coq,coq/coq,silene/coq,Zimmi48/coq,silene/coq,SkySkimmer/coq,silene/coq,Zimmi48/coq,coq/coq,coq/coq,ejgallego/coq,SkySkimmer/coq,gares/coq,Zimmi48/coq,gares/coq,coq/coq