Fix test on mono, failing because of difference in error string
Fix test on mono, failing because of difference in error string

  `Microsoft.Build.Tasks.UnitTests.Unzip_Tests.LogsErrorIfReadOnlyFileCannotBeOverwitten`

This brings back the fix that was reverted earlier:

	commit 620319992a26b108537f2daae0d5eb0c70b3c223
	Author: Ankit Jain <ankit.jain@microsoft.com>
	Date:   Tue Apr 30 15:21:17 2019 -0400

		[mono] Revert an old workaround which is not required anymore.

		Revert "[tests] Fix tests on mono, by using the correct error strings"

		This reverts commit 577912b5858d6b6f958a1cbfffe61c7cebe420fc.

mono/msbuild,mono/msbuild,mono/msbuild,mono/msbuild