Add more tests for setProfileNetworkPreferences

1. Test that adding a new preference replaces the existing preference.
2. Test that if we pass in two simultaneous preferences for the same user.
   (e.g., two different groups of apps), the second overrides the first.

Bug: 229644102
Test: ConnectivityServciceTest
Change-Id: I819247711f8457b12792585216ff47be31457ae8
1 file changed