hack/tests/sanity-check.sh: fail on changed go.mod and go.sum (#2098)

Author: joelanford

hack/tests/sanity-check.sh

@@ -1,18 +1,12 @@
 #!/usr/bin/env bash
 set -ex
 
-# Make sure repo is in clean state before running go tools
-git diff --exit-code
-
 go mod tidy
 go vet ./...
 go fmt ./...
 
 ./hack/check_license.sh
 ./hack/check_error_log_msg_format.sh
 
-# Ignore changes to go.mod and go.sum
-git checkout go.mod go.sum
-
 # Make sure repo is still in a clean state.
 git diff --exit-code