Fix prefix of mock hostpolicy on Unix (#23692)
Fix prefix of mock hostpolicy on Unix (#23692)

Fixes #23682
wtgodbe/coreclr,krk/coreclr,wtgodbe/coreclr,wtgodbe/coreclr,krk/coreclr,cshung/coreclr,poizan42/coreclr,wtgodbe/coreclr,poizan42/coreclr,cshung/coreclr,cshung/coreclr,cshung/coreclr,poizan42/coreclr,krk/coreclr,poizan42/coreclr,cshung/coreclr,krk/coreclr,krk/coreclr,wtgodbe/coreclr,krk/coreclr,cshung/coreclr,poizan42/coreclr,poizan42/coreclr,wtgodbe/coreclr