Restore setup-maestro-vars.ps1 (#4841)
Restore setup-maestro-vars.ps1 (#4841)

This was deleted in #4827 but that seems to be failing builds.
sean-gilliam/msbuild,cdmihai/msbuild,rainersigwald/msbuild,AndyGerlicher/msbuild,rainersigwald/msbuild,chipitsine/msbuild,mono/msbuild,mono/msbuild,AndyGerlicher/msbuild,mono/msbuild,cdmihai/msbuild,mono/msbuild,chipitsine/msbuild,sean-gilliam/msbuild,cdmihai/msbuild,sean-gilliam/msbuild,rainersigwald/msbuild,chipitsine/msbuild,rainersigwald/msbuild,cdmihai/msbuild,AndyGerlicher/msbuild,sean-gilliam/msbuild,AndyGerlicher/msbuild,chipitsine/msbuild