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
bbadec37d2