Swap the priority of UID_DEFAULT_UNREACHABLE and UID_DEFAULT_NETWORK

Let UID_DEFAULT_NETWORK has higher priority than
UID_DEFAULT_UNREACHABLE. Otherwise, the app will be told by
ConnectivityService that it has a network in step 1 of the scenario
below, which may potentially cause a user-visible error.

framework --> netd
step 1: add uid to OEM-paid network list
step 2: remove uid from unreachable network

Test: atest
Change-Id: I3fa49449b9d593b4a0346e8c2cb8d334628c0294