Remove safe mode for invalid entries in config (#8650)

The approach is that now safe mode is only invoked when
we cannot read the config or under some catastrophic
situations, but not under situations when config entries
are invalid or unreachable. This allows for maximum
availability for MinIO and not fail on our users unlike
most of our historical releases.

cmd/config/notify/parse.go

@@ -283,7 +283,7 @@ func RegisterNotificationTargets(cfg config.Config, doneCh <-chan struct{}, tran
 		// notification targets, based on their target IDs
 		for _, targetID := range targetIDs {
 			if !targetList.Exists(targetID) {
-				return nil, config.Errorf(config.SafeModeKind,
+				return nil, config.Errorf(
 					"Unable to disable configured targets '%v'",
 					targetID)
 			}
@@ -423,7 +423,7 @@ func GetNotifyKafka(kafkaKVS map[string]config.KVS) (map[string]target.KafkaArgs
 		}
 		kafkaBrokers := env.Get(brokersEnv, kv.Get(target.KafkaBrokers))
 		if len(kafkaBrokers) == 0 {
-			return nil, config.Errorf(config.SafeModeKind, "kafka 'brokers' cannot be empty")
+			return nil, config.Errorf("kafka 'brokers' cannot be empty")
 		}
 		for _, s := range strings.Split(kafkaBrokers, config.ValueSeparator) {
 			var host *xnet.Host