remove unuse code in cloudprovider

pkg/cloudprovider/plugins.go

@@ -60,18 +60,6 @@ func IsCloudProvider(name string) bool {
 	return found
 }
 
-// CloudProviders returns the name of all registered cloud providers in a
-// string slice
-func CloudProviders() []string {
-	names := []string{}
-	providersMutex.Lock()
-	defer providersMutex.Unlock()
-	for name := range providers {
-		names = append(names, name)
-	}
-	return names
-}
-
 // GetCloudProvider creates an instance of the named cloud provider, or nil if
 // the name is unknown.  The error return is only used if the named provider
 // was known but failed to initialize. The config parameter specifies the