Move network tests to new classes (1/n)

By classifying the tests into 2 categories, we can:
1) run remaining tests with network disabled to reduce the interference
   of network crashes.
2) make it easier to identify bugs caused by network stack or
   problems in rollback infra.

Note this CL contains stubs only. We will move actual test code later.

Bug: 147785893
Test: m
Change-Id: I5ecc63a057e9a115ea3aa446970a3f20dff750d0