Temporarily retry initial connect in test 400

There is a eluding issue that currently makes the
first request to the OpenStack Dashboard error out
with 500 Internal Server Error in CI.  Temporarilly
add retry logic to unwedge the gate.  This issue
should be revisited and root caused properly when time
allows.

Change-Id: Id828082416c7cbdd88247d9b6750c0f77467bc26