Explicitly end build in OutOfProcProjectInstanceBasedBuildDoesNotReloadFromDisk (#3554)
Explicitly end build in OutOfProcProjectInstanceBasedBuildDoesNotReloadFromDisk (#3554)

This appears to fix #3552. It's safe to remove the try/finally since
class setup/cleanup will handle `_buildManager`.
sean-gilliam/msbuild,AndyGerlicher/msbuild,Microsoft/msbuild,Microsoft/msbuild,AndyGerlicher/msbuild,rainersigwald/msbuild,rainersigwald/msbuild,cdmihai/msbuild,jeffkl/msbuild,chipitsine/msbuild,AndyGerlicher/msbuild,mono/msbuild,mono/msbuild,mono/msbuild,rainersigwald/msbuild,jeffkl/msbuild,sean-gilliam/msbuild,AndyGerlicher/msbuild,jeffkl/msbuild,jeffkl/msbuild,mono/msbuild,cdmihai/msbuild,cdmihai/msbuild,sean-gilliam/msbuild,rainersigwald/msbuild,cdmihai/msbuild,chipitsine/msbuild,Microsoft/msbuild,Microsoft/msbuild,chipitsine/msbuild,chipitsine/msbuild,sean-gilliam/msbuild