Make uid related tests compatible with Android Q

To be compatible with VPN isolation feature, DnsResolver has
different behavior fchown'ing when query socket.

sdk version >= (R+), fchown to apps' uid, otherwise fchown to AID_DNS

Make relevant tests compatible with it.

Test: atest
Bug: 161509097
Change-Id: I1c0bb4b9f35eaae32977a51c2d0a968092095cd0