Remove swift credentials from Jenkins slaves.

Glance "unit" tests previously connected to a remote swift object
store, but this test has not run in some time... known since the
credentials it was configured to use have been invalid for a while
and nobody noticed. These credentials are sensitive--or at least
would be if they were accurate--and thus should not be present on
Jenkins unit test slaves for security reasons.

Change-Id: Ic4341f7d53209af31c37a4207ab9eff00aa48879
Reviewed-on: https://review.openstack.org/25920
Reviewed-by: James E. Blair <corvus@inaugust.com>
Reviewed-by: Anita Kuno <akuno@lavabit.com>
Approved: Monty Taylor <mordred@inaugust.com>
Reviewed-by: Monty Taylor <mordred@inaugust.com>
Tested-by: Jenkins