Revert "Configure regional mirrors for our jobs"

Because /etc/nodepool directory doesn't exists on our zuul workers any
more. Remove this logic in favor of refactoring.

This reverts commit 2d9aab97828645e1bbae65ac481fc1dec4baf222.

Change-Id: Ie799942a8bf6e2558d6114f6418eb0b88ed40762
diff --git a/playbooks/roles/prepare-workspace/tasks/main.yaml b/playbooks/roles/prepare-workspace/tasks/main.yaml
index 26d0670..d8a5316 100644
--- a/playbooks/roles/prepare-workspace/tasks/main.yaml
+++ b/playbooks/roles/prepare-workspace/tasks/main.yaml
@@ -19,6 +19,3 @@
   synchronize:
     dest: "{{ prepare_workspace_root }}"
     src: "{{ zuul.executor.src_root }}"
-
-- name: Run configure_mirror.sh
-  shell: /opt/nodepool-scripts/configure_mirror.sh