Delete unnecessary internal method
Delete unnecessary internal method

This commit deletes an unnecessary internal method in
test_minimum_basic for simplification. It's easier to understand than
the original code.

Change-Id: Ic8b39ce46c3c1ca7421b72ba42e6257e903fbebb

cisco-openstack/tempest,bigswitch/tempest,masayukig/tempest,Tesora/tesora-tempest,Juniper/tempest,LIS/lis-tempest,vedujoshi/tempest,cisco-openstack/tempest,zsoltdudas/lis-tempest,Tesora/tesora-tempest,openstack/tempest,sebrandon1/tempest,sebrandon1/tempest,Juniper/tempest,LIS/lis-tempest,zsoltdudas/lis-tempest,openstack/tempest,vedujoshi/tempest,bigswitch/tempest,masayukig/tempest