Add inetutils-ping to test-deps

We require ping, and (amazingly) some hosts don't have ping - such as
ubuntu-minimal images.

Change-Id: I82b4ce15bffe6b164523a47151c01ef4ad190ab0

tests/install_test_deps.sh

@@ -4,5 +4,12 @@ set -eux
 set -o pipefail
 
 sudo apt-get update || true
-sudo apt-get install -y qemu-utils kpartx debootstrap || \
-    sudo yum -y install qemu-img kpartx debootstrap
+sudo apt-get install -y \
+        debootstrap \
+        inetutils-ping \
+        kpartx \
+        qemu-utils || \
+    sudo yum -y install \
+        debootstrap \
+        kpartx \
+        qemu-img