Do not call assumeTrue(isTelevision) in @After

Only call assumeTrue(isTelevision) during test setup (@Before), and do
not call it in teardown (@After), which causes tests to fail instead of
be slipped.

Bug: 171520419
Test: atest WMShellFlickerTests
Change-Id: I12f72d46a63c497686f0da7c4763ae79bbeb7dcd
1 file changed