Switching from ActivityInstrumentationTestCase2 to ActivityTestRule.

Leanback instrumentation tests are currently using deprecated
ActivityInstrumentationTestCase2 class. This CL replaces the deprecated
class with the recommeded approach - using ActivityTestRule.

We will have to make similar changes for other tests.

Change-Id: I647b1e5e1382f5cac96c7ccd56305ead3ffa721d
7 files changed