update go to 1.12 (#10382)

* update go to 1.12

* update per feedback

* fix test

* revert test changes

* remove zap.AddCallerSkip(1)

mlog/log.go

@@ -102,7 +102,6 @@ func NewLogger(config *LoggerConfiguration) *Logger {
 	combinedCore := zapcore.NewTee(cores...)
 
 	logger.zap = zap.New(combinedCore,
-		zap.AddCallerSkip(1),
 		zap.AddCaller(),
 	)