Fix legacy APIs when VPN switches to suspended underlying network.

Currently, when the VPN underlying network changes from a
network that is not suspended to one that is suspended (or vice
versa), some of the legacy APIs return incorrect results.

This is because the VPN's NetworkInfo can get into SUSPENDED
state even though the capabilities have the NOT_SUSPENDED
capability. This happens because the code in updateCapabilities
that checks for changes in NOT_SUSPENDED and NOT_ROAMING (which
are the capabilities that can affect the NetworkInfo state) is
only run when the capabilities change in a certain way.

Fix this by always checking for changes in these capabilities,
regardless of what else has changed.

This results in sending a lot more SUSPENDED and RESUMED
callbacks than the code sent previously. This should hopefully
not impact apps because those callback methods have never been
public API, though because they're just callbacks, it's possible
that apps found out via code inspection that the callbacks
existed and implemented them.

Bug: 172870110
Test: changes to existing tests in ConnectivityServiceTest
Change-Id: I6ec246a6a4e61f634956a165797fbb80296efd6a