yocto/oeqa: Modify LinuxLoginTest test

Modify test_linux_login test under LinuxLoginTest test class to
finish, under virtualization, only when every DomU guest has
reached the console, this is to allow the system to have full
performances as there should not be any other outstanding
computation left.

Update dictionary.

Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>