Fix DisplayAreaGroupTest

Before, setBounds doesn't really change the display orientation, it will
be reset to the actual bounds within the display rotation, so the test
passes only on device that is currently in portrait. Now, rotate the
display to portrait first.

Fix: 295865337
Test: atest WmTests:DisplayAreaGroupTest
Change-Id: I9e2338909c726135be08dc4313362df35e67ac30