tests, utils, delete vmi waiting: assert on err
tests, utils, delete vmi waiting: assert on err

Get could fail for other reasons then vmi is not found,
but when the eventually asserts on bool and fails, we could miss that.
For that Eventually should assert on the error returning from Get().

This commit changes the eventualy in
`waitForVirtualMachineToDisappearWithTimeout` to assert on the error.

Signed-off-by: alonSadan <17e3534da4e06ee40320bd1687715e3dda4806ac@redhat.com>

stu-gott/kubevirt,davidvossel/kubevirt,stu-gott/kubevirt,kubevirt/kubevirt,davidvossel/kubevirt,kubevirt/kubevirt,davidvossel/kubevirt,stu-gott/kubevirt,stu-gott/kubevirt,kubevirt/kubevirt,davidvossel/kubevirt,kubevirt/kubevirt