Revert "See if explicitly creating SLDR cache folder will enable test…

… setup to succeed consistently on Appveyor"

This reverts commit 7ec02ef.

SIL.WritingSystems.Tests/SldrTests.cs

@@ -18,8 +18,6 @@ private class TestEnvironment : IDisposable
 			public TestEnvironment(bool sldrOffline = true, DateTime? embeddedAllTagsTime = null)
 			{
 				var sldrCachePath = Sldr.SldrCachePath;
-				Directory.CreateDirectory(sldrCachePath);
-
 				Sldr.Cleanup();
 				if (embeddedAllTagsTime == null)
 					Sldr.Initialize(sldrOffline, sldrCachePath);