Revert "add lock (apache#1304)" (apache#1329)

This reverts commit a109967.

Author: LaurenceLiZhixin

config/config_loader.go

@@ -441,8 +441,6 @@ func GetApplicationConfig() *ApplicationConfig {
 // if not found, create new one
 func GetProviderConfig() ProviderConfig {
 	if providerConfig == nil {
-		configAccessMutex.Lock()
-		defer configAccessMutex.Unlock()
 		if providerConfig == nil {
 			return ProviderConfig{}
 		}
@@ -457,8 +455,6 @@ func GetProviderConfig() ProviderConfig {
 // So you don't need to worry about the race condition
 func GetConsumerConfig() ConsumerConfig {
 	if consumerConfig == nil {
-		configAccessMutex.Lock()
-		defer configAccessMutex.Unlock()
 		if consumerConfig == nil {
 			return ConsumerConfig{}
 		}