Change truststore location in test runner

libcore says java.home is /system, so the truststore path should be
/system/etc/...

This worked on existing android devices because they symlink /etc to
/system/etc. Googletv doesn't symlink, but the test should mimic
reality and look in /system/etc

Confirmed on moto xoom and googletv

Change-Id: I5a7db6842e60ab3aa141d1dc72452ecc47f8fd84
1 file changed