Cleanup and rename test_create_ebs_image_and_check_boot
Cleanup and rename test_create_ebs_image_and_check_boot

I'm trying to debug a failure in a nova change
in test_create_ebs_image_and_check_boot but
need more debug information, specifically the
volume details when it fails. While doing this,
I'm going to cleanup the comments and variable
names so this test can actually be understanble.

Also, this renames the test itself since the 'ebs'
part (AWS Elastic Block Storage) has long been a
source of confusion.

Change-Id: I4d60adc95d72be609927e36a28fd7c86b5ee86bc
Related-Bug: #1747693

openstack/tempest,cisco-openstack/tempest,masayukig/tempest,cisco-openstack/tempest,openstack/tempest,masayukig/tempest