Rename test_delete_image_id_is_over_35_character_limit
Rename test_delete_image_id_is_over_35_character_limit

The "35" in test_delete_image_id_is_over_35_character_limit should
be "36", because valid uuid length is 36. Here we can just
name it as "test_delete_image_with_id_over_character_limit".

Besides, this is also to use data_utils.rand_uuid() to generate
invalid uuid, thus to make code more readable.

Change-Id: If64d2bafa0bfab8a4f15ed59a403bb775d6b3f38

cisco-openstack/tempest,vedujoshi/tempest,Juniper/tempest,masayukig/tempest,openstack/tempest,cisco-openstack/tempest,Juniper/tempest,masayukig/tempest,vedujoshi/tempest,openstack/tempest