Make hack scripts use go install and assume PATH

Now that they all call setup_env, we don't need find-binary (I think).
That was originally meant to hide the diff between docker and local
builds but all these tools do local builds anyway.

hack/verify-cli-conventions.sh

@@ -27,7 +27,7 @@ source "${KUBE_ROOT}/hack/lib/init.sh"
 
 kube::golang::setup_env
 
-hack/make-rules/build.sh ./cmd/clicheck
+GOPROXY=off go install ./cmd/clicheck
 
 if ! output=$(clicheck 2>&1)
 then