Add java flags from external/robolectric-shadows/robotest.sh to tradefed template

Add the same flags as external/robolectric-shadows/robotest.sh to
robolectric_test_config_template.xml so they apply to tests run
with atest or the test infra too.

Test: atest --host MyRoboTests
Change-Id: Iaac2dc30b82e6fcdc028e9dcdfaf0b1c7e9a2ba3