test: twister: fix false negative in device test

in device test when harness is Test, if there is no console output,
the self.state is None, as at this time self.instance.state
is "pass", as the last step cmake is "pass". So it will report "pass",
but actually there is no console output issue

you can easily reproduce this issue by set
line='' at the begining of the Test.handle function

fixing: #45942

Signed-off-by: Hake Huang <hake.huang@oss.nxp.com>