update go to 1.12 (#10382)

* update go to 1.12

* update per feedback

* fix test

* revert test changes

* remove zap.AddCallerSkip(1)

scripts/prereq-check.sh

@@ -35,7 +35,7 @@ echo "Checking prerequisites"
 
 REQUIREDNODEVERSION=8.9.0
 REQUIREDNPMVERSION=5.6.0
-REQUIREDGOVERSION=1.11.0
+REQUIREDGOVERSION=1.12.0
 REQUIREDDOCKERVERSION=17.0
 
 NODEVERSION=$(sed 's/v//' <<< $(node -v))