Update version check for notifyNetworkTested() call.

NetworkMonitor checks the version of INetworkMonitorCallbacks used by
the platform before invoking notifyNetworkTested() or
notifyNetworkTestedWithExtras(). The version number used for checking is
currently 5. However, this should be changed to 4, as the functionality
for notifyNetworkTestedWithExtras() is actually being added in version 5
of the callback.

Bug: 148032944
Test: atest NetworkStackTests
Test: atest android.net.cts.ConnectivityDiagnosticsManagerTest
Change-Id: I2337120fe70f75c072a9286038e66065fddcf857