Move ConnectivityDiagnosticsManagerTest to common

The tests are also useful in CTS to ensure that the
ConnectivityDiagnosticsManager class API is implemented properly
(including behavior of the DataStallReport class for example).

Bug: 187935317
Test: atest ConnectivityDiagnosticsManagerTest
Change-Id: I86f39238054f43403f9a1e383dd2a935de84f06f
1 file changed