Revert "Purge the unattended-upgrades pkg"

This reverts commit d81b23c4ce3eb6c753119c50f5c0ec0a5155ed8a.

Change-Id: Iad2e43e3be3e468a4df88f5ccd7b60cc3cbfac32
diff --git a/tcp_tests/templates/shared-salt.yaml b/tcp_tests/templates/shared-salt.yaml
index 2d06193..95f207a 100644
--- a/tcp_tests/templates/shared-salt.yaml
+++ b/tcp_tests/templates/shared-salt.yaml
@@ -62,8 +62,7 @@
     echo "{{ UBUNTU_REPOSITORY }}" > /etc/apt/sources.list.d/ubuntu.list
     echo "{{ UBUNTU_UPDATES_REPOSITORY }}" > /etc/apt/sources.list.d/ubuntu_updates.list
     echo "{{ UBUNTU_SECURITY_REPOSITORY }}" > /etc/apt/sources.list.d/ubuntu_security.list
-    eatmydata apt-get clean;
-    apt-get update;
+    eatmydata apt-get clean && apt-get update;
     sync;
   node_name: {{ NODE_NAME }}
   retry: {count: 1, delay: 5}