This change updates ConnectivityService to use IBinder instances as keys
when storing ConnectivityDiagnosticsCallbacks.
When storing ConnectivityDiagnosticsCallbacks in ConnectivityService,
the IConnectivityDiagnsoticsCallback is used as the key for
ConnectivityService.mConnectivityDiagnosticsCallbacks. However,
IConnectivityDiagnosticsCallback instances are received as different
objects. This causes them to produce different hashCode() values, so
attempts to remove an IConnectivityDiagnosticsCallback fail.
Bug: 150867635
Test: atest FrameworksNetTests
Change-Id: Ib99e68d5ae47fa27e12428f9a60a2c1204ac59a2
31f1ff693b