Don't run dep prune, configure prune in Gopkg.toml

Gopkg.toml

@@ -60,3 +60,8 @@ required = [
 [[constraint]]
   name = "k8s.io/client-go"
   version = "kubernetes-1.10.0"
+
+[prune]
+  go-tests = true
+  unused-packages = true
+  non-go = true

hack/update-deps.sh

@@ -25,11 +25,9 @@ trap popd EXIT
 
 # Ensure we have everything we need under vendor/
 dep ensure
-dep prune
 
 rm -rf $(find vendor/ -name 'BUILD')
 rm -rf $(find vendor/ -name 'BUILD.bazel')
-rm -rf $(find vendor/ -name '*_test.go')
 
 # Make sure that BUILD files are up to date (the above removes them).
 bazel run //:gazelle