Stop passing redundant params in official build (#3493)
Stop passing redundant params in official build (#3493)

After #3480 simplified the dev-inner-loop invocation of `build.cmd`, the
official build broke because it passed `-skiptests -bootstraponly`
twice.

I made this change in the non-YAML build which isn't tracked;
making it here in YAML as well.
chipitsine/msbuild,AndyGerlicher/msbuild,mono/msbuild,Microsoft/msbuild,mono/msbuild,jeffkl/msbuild,sean-gilliam/msbuild,chipitsine/msbuild,jeffkl/msbuild,rainersigwald/msbuild,cdmihai/msbuild,Microsoft/msbuild,rainersigwald/msbuild,AndyGerlicher/msbuild,sean-gilliam/msbuild,rainersigwald/msbuild,sean-gilliam/msbuild,Microsoft/msbuild,mono/msbuild,mono/msbuild,cdmihai/msbuild,rainersigwald/msbuild,chipitsine/msbuild,jeffkl/msbuild,sean-gilliam/msbuild,chipitsine/msbuild,AndyGerlicher/msbuild,AndyGerlicher/msbuild,jeffkl/msbuild,cdmihai/msbuild,cdmihai/msbuild,Microsoft/msbuild