[Testing] Use AndroidJUnit4 instead in NetworkDashboardFragmentTest

1. Use AndroidJunit4 instead of RobolectricTestRunner
2. Use ApplicationProvider instead of RuntimeEnvironment to get context
3. Change Copy Right
4. Run the NetworkDashboardFragment on the Main thread

Bug: 168000627
Test: atest -c NetworkDashboardFragmentTest
Change-Id: I6d10737b9ac8299f2d7c847a9fdb1c3bdc4e390d
1 file changed