CTS for default background network restrictions

Apps will now lose network access once they are in top-sleeping or
higher process state. Adding some cts tests to ensure correct behavior.

The tests are using temporarily using junit Assume to skip if the
feature flag is enabled to enable a following code migration.

Test: atest CtsHostsideNetworkTests

BYPASS_INCLUSIVE_LANGUAGE_REASON=Existing method

Bug: 304347838
Change-Id: Iba7c7bd01309fa7a301fdc1524033f0fad5ae512