CA: update-deps.sh: move tidy after all gets

There doesn't seem to be any benefit to tidying after
getting every dependency pkg. And trying to tidy after
every get seems bugged:

* Some of the k8s.io dependencies depend on each other.
  For example k8s.io/client-go depends on k8s.io/api.
* We bump k8s.io/api to a new version, and that version removes
  some pkg (e.g. replaces v1alpha1 with v1alpha2), that
  some other dependency (e.g. k8s.io/client-go) requires.
* If we try to tidy immediately after getting k8s.io/api, this can
  fail because the required new k8s.io/api version doesn't have the
  removed pkg that k8s.io/client-go (still at a lower version
  since we haven't processed it yet) requires.

Getting all of the dependencies at the new versions first, and then
tidying once afterwards solves this issue.

cluster-autoscaler/hack/update-deps.sh

@@ -90,10 +90,11 @@ cluster_autoscaler:update_deps() {
       go mod edit "-replace=${mod}=${mod}@${mod_version}"
     else
       go get "${mod}@${mod_version}"
-      go mod tidy
     fi
   done
 
+  go mod tidy
+
   if [ "${pkg}" = "./cluster-autoscaler" ]; then
     go get "k8s.io/kubernetes@v${k8s_version}"
     go mod tidy