updated tests for creating a mirror to be in line with 'create new'+save approach instead of addMirror(xyz)
updated tests for creating a mirror to be in line with 'create new'+save approach instead of addMirror(xyz)

this is more natural for an angular-based implementation

Signed-off-by: Dominik Richter <b7323add517e187efe0283b76511b7ed762bfe13@gmail.com>

TelekomCloud/postrider