Add a unit test for a bug in registerDefaultNetworkCallback.

Currently, when a VPN app calls registerDefaultNetworkCallback,
it will always get its own VPN, even if the VPN app called
VpnService.Builder#addDisallowedApplication to take itself out
of the VPN's UID ranges.

Add a test for the current incorrect behaviour.

Also fix an indentation error elsewhere.

Bug: 195265065
Test: test-only change
Change-Id: Id9648ea71fc7ae10855aa311beeb7975569d17f2
1 file changed