tests: Remove 'default_states' fixture requirement

tests: Remove 'default_states' fixture requirement

The 'default_states' fixture is used in many tests. However, the
'default_states' are merely suggestions for various States, and the
names themselves have no meaning from a patchwork perspective. In
addition, these fixtures significantly increase run time of the tests.

Resolve this by creating new State objects on demand, rather than
using versions provided by the fixture.

Signed-off-by: Stephen Finucane <stephen.finucane@intel.com>
Reviewed-by: Andy Doan <andy.doan@linaro.org>