Currently, running the defcore test set fails on a couple of tests due
to incorrect tempest.conf configuration. This commit does the
following to address:
1. Creates new tempest_network_tenant_network_cidr and
tempest_network_tenant_network_mask_bits role defaults
In tempest.conf, tenant_network_cidr expects to be a bigger network
which it can create smaller subnets from using
tenant_network_mask_bits. We currently set tenant_network_cidr to
'192.168.74.0/24' with a tenant_network_mask_bits of '24', which
obviously won't work. The var tempest_network_tenant_network_cidr now
defaults to '192.168.74.0/24'
and tempest_network_tenant_network_mask_bits defaulting to '28'. The
actual tenant network (tempest_private_subnet_cidr) that we create is
now '192.168.74.0/28', which fits into tenant_network_cidr.
2. Creates new tempest_compute_ssh_user role default
Some tests were failing as they were attempting to ssh to booted
instances using username 'root', which was confusing as we already set
image_ssh_user to 'cirros'. Oddly, it was attempting to use the
tempest config ssh_user so setting that to cirros also ensures those
tests pass.
Change-Id: Ib6396d765bc974675ed3841a1f22cb75ea8fce5a
f16bb31008