CHERRY-PICK: [Whale] Fix the internal state broken by NUC.

NUC StopFixture() Function in whale_bft_fixture.py will break the
internal state of interrupt_handler.py.

BUG=None
TEST=test on Whale

Change-Id: I81157562ee13d049b5ad9b7cc6c412a09b3cd3b7
Original: Change-Id: I4599e4fe14f40763b4ba3d3f8e5bbf4eb2ab5355
Original: Reviewed-on: https://chromium-review.googlesource.com/241866
Original: Reviewed-by: Pin-chih Lin <johnylin@chromium.org>
Original: Tested-by: alastair jiang <alastair.jiang@quantacn.com>
Original: Commit-Queue: alastair jiang <alastair.jiang@quantacn.com>
Reviewed-on: https://chromium-review.googlesource.com/249644
Reviewed-by: Shuo-Peng Liao <deanliao@chromium.org>
Commit-Queue: alastair jiang <alastair.jiang@quantacn.com>
Tested-by: alastair jiang <alastair.jiang@quantacn.com>