Potential fix for flaky tests.

1) Fixing orientation of test devices to their natural orientation
(Phone is usually portrait, and most big tablets are landscape). We
unfreeze the orientation at tearDown because if we don't, the device
will be permanently locked to that orientation.
2) Adding closerDrawer() to FileManagementUiTest and RootsUiTest.

Bug: 30190207
Change-Id: Iec90ee8d46fef1acbf5b04fe718810edbf99da0c