update go to 1.12 (#10382)

* update go to 1.12

* update per feedback

* fix test

* revert test changes

* remove zap.AddCallerSkip(1)

build/Dockerfile.buildenv

@@ -1,3 +1,3 @@
-FROM golang:1.11
+FROM golang:1.12
 
 RUN apt-get update && apt-get install -y make git apt-transport-https ca-certificates curl software-properties-common build-essential zip wget xmlsec1