Protect failed setUidPolicy() and avoid storing invalid UIDs

Add protection for the setUidPolicy() failed case to avoid invalid UIDs
to crash the caller process, and avoid storing the invalid UIDs to
SharedPreferences if it is failed to setUidPolicy()

Bug: 306329984
Test: make -j64 RunSettingsRoboTests ROBOTEST_FILTER="com.android.settings.fuelgauge"
Change-Id: I5c14434708b82ba3c238c2338d47085c2ce244e0