Set default caching level to None (#1748)

(cherry picked from commit ae8bfae)

src/LanguageServer/Impl/LanguageServer.Configuration.cs

@@ -180,7 +180,7 @@ private ImmutableArray<string> GetUserConfiguredPaths(JToken pythonSection) {
             return ImmutableArray<string>.Empty;
         }
 
-        private const string DefaultCachingLevel = "System";
+        private const string DefaultCachingLevel = "None";
 
         private AnalysisCachingLevel GetAnalysisCachingLevel(JToken analysisKey) {
             var s = GetSetting(analysisKey, "cachingLevel", DefaultCachingLevel);