Fix legacy failed tests to avoid block presubmit

Root cause: the `Robolectric.setupActivity(Activity.class)` is removed from the system, which will always return the null `Context`

Test: make RunSettingsRoboTests ROBOTEST_FILTER=com.android.settings.fuelgauge.*
Change-Id: Ib52bc715508332bcb4bdcac56ecc414aa43f1419