Log: Improve feature deprecation/removal logs (#3793)

* Improve feature deprecation/removal logs

* Add a note about the new feature

* When the feature has removed, this should be an error not a warning

features/feature.go

@@ -18,5 +18,10 @@ type Feature interface {
 
 // PrintDeprecatedFeatureWarning prints a warning for deprecated feature.
 func PrintDeprecatedFeatureWarning(feature string) {
-	errors.LogInfo(context.Background(), "You are using a deprecated feature: " + feature + ". Please update your config file with latest configuration format, or update your client software.")
+	errors.LogWarning(context.Background(), "You are using a deprecated feature: " + feature + ". Please update your config file(s) with latest configuration format, or update your client software.")
+}
+
+// PrintRemovedFeatureError prints an error message for removed feature. And after long enough time the message can also be removed, use as an indicator.
+func PrintRemovedFeatureError(feature string) {
+	errors.New("The feature " + feature + " is removed. Please update your config file(s) according to release notes and documentations.")
 }