VS: Revert "Use MSBuild matching toolset host architecture"

Revert commit da402a08 (VS: Use MSBuild matching toolset host
architecture, 2019-01-28, v3.14.0-rc1~50^2).  Multiple people have
reported that the 64-bit `amd64/msbuild` tool fails in cases that the
32-bit `msbuild` works.  Drop our change pending further investigation
and hopefully a fix to VS.

Fixes: #18904, #19037
Issue: #18219
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