[Roboelectric] Split Robolectric frameworks services targets

1. Move all backup tests from services/robotests/src to services/robotests/backup/src
2. Copied over services/robotests/backup/config/robolectric.properties
3. Copied and modified services/robotests/backup/Android.mk

Bug: 120223382

Test: 1) atest RunFrameworksServicesRoboTests (backup + location). out: RunFrameworksServicesRoboTests: OK (615 tests)
2) atest RunBackupFrameworksServicesRoboTests (backup). out: RunBackupFrameworksServicesRoboTests: OK (582 tests)

Change-Id: I2b0c95b22e90b01f715f772c60c2179b8c0eb29b