Add delete image member and delete image negative tests

*Updated delete image member module to reflect cloud cafe changes
*Updated delete image negative module to reflect cloud cafe changes
*Updated modules aesthetic consistency
*Removed happy_path from test name
*Updated id to image_id for better readability
*Added validation step for image member
*Removed delete_members module as the tests are covered in the delete_image_member module

Change-Id: Ie90a39c3621b41c5e9692bb17b561fbbd1b1700f
Merge "Add delete image member and delete image negative tests"